Ideas for a women's 50th weekend please?

[BenWillbondsPants]

A friend and I are trying to arrange a 50th weekend away for a friend. She knows it's happening but the rest is up to us. So we need some ideas for activites, location (north ish London/Cambridge area or surrounding is fine and it will be in a warmer month (hopefully!). Not tooooo expensive. There will probably be about 15 of us in all.

Any ideas?

Afternoon tea.
Punting, if Cambridge.
LLama walking.
Pottery painting.
Walking over the O2 Arena, if London.
Escape Room.
Adult ball pond, if London. Cant remember where exactly it is, maybe Shoreditch.
Hot air balloon ride, but these can be unreliable as often cancelled due to the weather.

So many people?? Hire a big house on a beach and just relax and hang out. Barbecue, board games, cycling. Lots of cake and alcohol. Nothing too formal or compulsory.