we travel on Tues to Brentwood, so will be there in the afternoon, we have tickets to harry potter at 3 on wed, and then all of thurs free, before travelling back home friday morning.
So, what is child friendly / exciting (cheap! FREE!!) that we could do?
DH just said 'ask mumsnet' so you are honoured!! 
dcs are 8 and 5
So far we have:
British museum
changing of guard
Westminster cathedral has list at £2 to look out at top of spire rather than london eye as I think dd will be terrified so dh can zip up with ds.
Open top bus tour for dcs!
planning to get oyster or travel cards for tube travel
Any other good stuff, recommended eateries in london or at the brent cross side so we're not just in the hotel all appreciated
thanks in advance 