Large weekend cottage near London?

[littlestar]

I'm trying to organise DH's 40th birthday in October....he wants a weekend away in the country or by the sea. We need a house that can accommodate 4 or 5 couples + 8 kids (the kids can all sleep together in 1 or 2 rooms). We don't have a huge budget and ideally we'd like to be within a couple of hours of London.

I haven't done this kind of thing for years so would really appreciate any recommendations or ideas...