If you are stuck for something to do with the DC on Halloween, Stanley Hall (SE25)are showing Frankenweenie this Friday. The event starts at 1pm with face painting and lots of other activities.
It's part of the free film festival that is currently on - www.freefilmfestivals.org/whats-on/south-norwood-thornton-heath/details/356-halloween-special.html
There is also a spooky event for us grown-ups in the evening (I'll have to find a babysitter).