I would have a look at all the local town halls / Church halls, they are usually available on Sundays and are pretty cheap. I know there is a really good one in Wimbledon especially. Chelsea Old Church has the Petyt Hall which is a fab venue (just by Battersea Bridge).
If you are looking for a caterer, I have my own catering company, based in Battersea, called
Scarlett's Pantry. Have a look at my website
www.scarlettspantry.co.uk
I do lots of Christening lunches / teas, and have lots of delicious and fun ideas. I also make Christening cakes and cupcakes.
Please do get in touch if you are interested in talking further. My email address is
scarlett@scarlettspantry.co.uk or call me on 07733 226 619.
Scarlett's Pantry is a boutique catering company creating homemade and scrumptious dishes and cakes.