im not really answering your question but just wantd to say we stay in london about 4 times a year and always pay for our hotel with our clubcard deal vouchers and just end up paying the odd maybe �8 - �10 in cash otherwise we go courtesy of tesco! i believe they are cheaper at weekends but not really sure - we can only go at weekends as we work. also dont forget the 2 for 1 vouchers when you buy a rail ticket, we have some wonderful days there and it really doesnt cost much at all.