Ideas for fun Easter holiday activities for children aged 8 to 12

[Tangerinesattack]

Could we have a thread of ideas for fun activities to do over the Easter holidays for slightly older children, say ages 8 - 12? Cheap or free is always good, but not essential . Off the top of my head, we've had success with foraging and making something with the results, hikes with a camping stove to cook lunch on, cinema afternoon with homemade popcorn and snacks, boardgames tournament.

My children are 9 and 13 and we have planned so far:

Cinema trip - sweets/popcorn will be bought cheaply from Homebargains beforehand (an activity in itself!) and I used a Meerkat code to make it cheaper.
Shopping morning/afternoon (they have birthday/pocket money to spend) We will most likely buy breakfast or lunch depending on what time we go.
Day out - cost £60 for all 4 of us and we will be taking a picnic to reduce costs

The rest of the time will be screen time, Lego, colouring/crafts, parks, walks, swimming, pottering about seeing relatives, little shopping trips to the local outlet/supermarket/garden centre etc that are free/cost very little and if the weather is good we plan to sort the greenhouse, get compost, tomato plants etc.