My sons (the eldest now 9 has been going since he was just 4) absolutely love this club, so I thought I would give it another mention - quite a few parents I know haven't seemed to know what's on over the summer childcare-wise.
Link for more info and booking is www.nimblearts.co.uk
It runs from 8am-6.30pm (movie club from 5pm is optional for small extra fee).
They have a breakfast bar with snacks, fruit and drinks in case you've had a manic morning or the kids are still peckish when dropped off.
There is a different theme daily (and a permanent bouncy castle in situ!). The kids are split by age and the supervision is excellent in my experience - with many having teaching or TA experience.
So far in the club my boys have held exotic animals, learned some magic and circus skills, done lots of arts and crafts (from drawing to making clay crocodiles!) and loads of fun games.
It's a little more expensive than some others but they use high quality materials and have a lot more supervision from what I have seen (when compared with other clubs, who tend to hire students or people without any close experience working with children and understanding their needs - whatever their age!!).
Highly highly recommended, like stepping into a Blue Peter set when I pick them up (oh and they never want to come home - always a good sign