Ideas for days out for older dc - London/Home counties

[Dancergirl]

My older two are 12 and 10.5 (also have a 6 year old). I'm struggling to find places to go that they'll all enjoy.

Any ideas around London/Herts/Bucks?

We are also NT members.

This isn't really a day out but I've just been to see groove on down the road on the southbank and it was amazing. Any child or adult would love it. Totally brilliant. You could have an amble around southbank eat them see that.

Tried geocaching? www.geocaching.com great for finding new places to go

Hendon RAF museum
Lea Valley watersports centre
Ashridge Estate NT park
Bletchley Park (home of Enigma machine)
Waddesdon Manor NT house and park
Luton Inspire Swimming Centre (50m pool and diving boards)
Knebworth Park
Grand Union Canal walks or boat trips near Berkhamsted
Thames river trips (commuter services, using Oyster card)
Emirates air line cable car
Thames Barrier - exhibition, walks, nature reserves
Wetlands Centre near Barnes
Kenwood House
Museum of London at the London Wall
Maritime Museum in Docklands
Geffrye Museum
Walking on the Thames 'beach' at low tide on the south bank

(my DSs are 11 and 9 and love all these things)