Where can i go for this bank holiday?

Travel Info
I live in London and i was planning to take my kides and wife out to vist some places in London, but I heard that the weather is going to be very bad, so any sugesstion where can I go (indoors)?

Thanks

Travel Tips

Go see The Cutty Sark.
Others

Skegness, Witby, or how about a nice walk in the lake district?

The world's your oyster! (until Tuesday anyway. Damned work!)
The science museum. Lots of things for them to see and touch and they have (or at least had when I went there last) two simulators which were fantastic fun!!!

They'll also learn stuff as well.
The Underground is mostly dry, but the scenery is a bit repetitive.
Pack a mack and go to the Isle of Wight, fun for all the family.
It was in the 50s when I was a kid,and it is now.
Hampton Court.