Surrey: the Big Picnic at Hampton Court Palace, 25-27 May

Head over to Hampton Court Palace over the long weekend, but don't forget your sandwiches and scotch eggs, as all ticket holders are invited to join a mass picnic in the grounds. Admittedly, the agenda doesn't sound particularly appetising – offering picnickers the chance to meet a blood-sucking leech and have a "smallpox makeover". But plenty of gruesome tales over lunch means kids will enjoy it far more than the usual riverside picnic. For those with more refined tastes, there's a Pimm's bar and cream teas, as well as a barbecue for those who forget their hampers.
• 0844 482 7777, hrp.org.uk, adults £16.50, children free

Bristol: Upfest, 25-27 May

It's hard to mention Bristol street art without mentioning a certain graffiti artist that comes from the area. But so much great street art has sprung from here, both before and after Banksy started stealing all the headlines. So much so that the city has a well-established urban paint festival, Upfest. Now in its sixth year, the event has an emphasis on live demonstrations, rather than just admiring local murals (which you can do anytime, solo or with Bristol Street Art Tours). For one weekend only, the city is making way for 250 artists from across the world, who will take part in live painting and illustration battles, plus there's music across four stages and a variety of food stalls. Family activities include face-painting for younger kids and spray paint workshops for older ones.

Also in Bristol, from 24-26 May, is VegFestUK, Britain's leading veggie festival, where aside from plenty of food, there'll be live music from performers not usually associated with healthy lifestyles, including Happy Mondays, Peter Hook and 808 State.
• Upfest at the Tobacco Factory and throughout North Street, from 11am until 8pm, free. VegFestUK at Amphitheatre and Waterfront Square. Ticket pricing is somewhat complicated, depending on the time and day (from £2 to £25) – check bristol.vegfest.co.uk for details

Cornwall: Superheroes Day at Crealy Great Adventure Park, 28 May

Pinning their superhero celebration to the release of a new Superman film (Christopher Nolan's Man of Steel), Crealy Great Adventure Park is offering a loose but perfectly acceptable excuse for getting dressed up in tights. All ages are encouraged to get into the spirit of Tuesday's theme, but it's kids who'll receive half-price entry for dressing up as their favourite comic book character or cartoon character. Superman, Batman and Captain America will be appearing throughout the day. The park, near Newquay, also has 40-plus regular rides and attractions for three to 13-year-olds, including a brand-new reptile house, Crocodile Corner, and 40,000 sq ft of indoor play areas, which could come in very handy if the weather turns.
• Near Wadebridge, 01841 540 276, crealy.co.uk, family of three £40.68, family of four £54.24 (online ticket prices)

Pembrokeshire: Oakwood Theme Park

Oakwood Theme Park is celebrating another family favourite: Peter Pan. Neverland, their new £4m attraction, will be up and running in time for half term. Spread over three acres, it includes a pirate-themed log flume, a crocodile rollercoaster, Hook's House of Havoc soft play and a Sights of London taxi ride, featuring Big Ben, the Tower of London and Nelson's Column. Older visitors seeking a few more thrills shouldn't miss Megafobia, often said to be one of the world's best wooden rollercoasters.
• Oakwood Theme Park, Narberth. Adults £19, children £13, family of four £59 (online ticket prices)

West Sussex: Arundel Castle 25-27 May

If you live in – or near – West Sussex, avoid doing battle with the usual bank-holiday traffic and stay closer to home to witness a fight of a different sort: Arundel Castle's three-day enactment of a battle between the Houses of Lancaster and York. Though such a siege never actually happened here, the idea is to give visitors a sense of life during the War of the Roses and how it would have felt for the castle to come under threat. Over 200 participants from the Raven Tor Living History Group will be dressed in replica outfits, plus they'll be medieval craft demonstrations and 14th-century armour to try on. Expect plenty of cannons and combat on the edge of the river Arun.
• arundelcastle.org, tickets £8, free for under 5s

Plymouth: pirate weekend, 25-26 May

Landlubbers are invited to get a taste of life as a pirate in Plymouth over the bank holiday weekend. Historical ship the Bessie Ellen will be berthed in Sutton Harbour, and visitors will have the chance to go on board to explore (free, from 10am to 4pm) with a costume competition judged daily at 3pm. There's also a treasure hunt through the area – download the map on visitplymouth.co.uk or pop into the Barbican-based tourist office. Plus there'll be sword-fighting demonstrations, a pirate-themed puppet show, face painting and craft workshops around the harbour and Barbican.
• Barbican and Sutton Harbour, from 10am to 4pm, free, visitplymouth.co.uk

Northumberland: Hadrian's Wall, 28 May-2 June

Enroll at Roman soldier school to mark 10 years since Hadrian's Wall Path was relaunched as a national trail. Maximus, the centurion, will be leading activities that include making paper Roman helmets, handling ancient artefacts, dressing up and taking part in a Roman drill. There are various other events along the wall, including walks along the Cumbrian section. • Housesteads Roman Fort, near Bardon Mill, visithadrianswall.co.uk. Adults £6.20, children £5.60, English Heritage members free

Leeds: Food Festival, 24 May-9 June

You've got a window of more than two weeks to visit the Leeds Loves Food festival, as well a range of over 50 venues to choose from. There's pop-up dining and cocktails in the Trinity shopping centre, the chance to show off your baking skills during the Great Leeds Bake Off, blind whisky tasting, a night food fair, and all manner of food stalls. Masterchef finalist Sara Danesin-Medio will also be giving a cooking demonstration and serving dinner to a lucky few at the Northern Ballet Dinner Club. The event culminates in the final weekend (7-9 June) with the Yorkshire Food and Drink Show in Millennium Square. See leeds-list.com for a mouth-watering look at the highlights.
• See visitleeds.co.uk for many free events and some ticketed dinners

Portrush, Northern Ireland: raft race, 25-26 May

This local tradition is in its 32nd year, and around 80 homemade rafts are expected to fill the waterfront. Many are imaginative, lots are colourful, some are just plain silly, but all have the primary aim of staying afloat from the West Strand beach to Portrush harbour. Fortunately, the RNLI – who run the event – is on hand throughout, just in case. There's a festival atmosphere and no shortage of entertainment along the quay. There's a waiters' race, too, which takes place in the harbour on Sunday at 3pm and is also quite the spectacle, with lots of fancy dress and crowd participation.

• portrushraftrace.co.uk, free

Wiltshire: Sunrise festival, 30 May-2 June

The poor crowd at Sunrise festival didn't see much sun last year, when the British weather turned the site into a mud bath. This year, organisers vow to make it more watertight, having moved from their site on an organic farm in Somerset to Thoulston Park, Wiltshire. Said to be the most sustainable festival in the UK, it is powered entirely by renewable energy (including waste vegetable oil). There's even a solar-powered dance stage. Let's hope they have some sort of back-up, just in case. The Storylands area will keep the kids entertained, and there's music across 10 stages, with a line-up including Dub Pistols, Krafty Kuts and the Beat.
• sunrisefestivals.co.uk, adults £115, children £25, family tickets £255

London and beyond: Chelsea Fringe, 18 May-9 June

There must be something in the water, because Chelsea Fringe has certainly grown in its second year, now sprouting some 200 projects as offbeat alternatives to the Chelsea Flower Show. Moving far beyond SW3 and spreading right across the capital and beyond – including Bristol, Canterbury and even Vienna, the three-week event is already well underway. The botanical garden-inspired gin bar sounds like a fine idea, but more child-friendly activities include a treasure hunt through Chiswick herb gardens and a dog show at Inner Temple Garden. But the pick of the crop has to be the tie-in events with Battersea Power Station, primarily because it makes the perfect excuse for visiting its new pop-up park (open until September).
• chelseafringe.com