It La Lanterna restaurant on Mill Street, SE1
http://www.millstreetcafe.co.uk/
7pm £30 per head for three courses plus coffee. Wine additional but a bottle of good house wine is around £10.
Spoke to the chap at the Italian - they can provide a room for 30-40 people (more if needed). Am going back Friday evening to chat through costs. Reckon should get three courses for about £20 plus the house wine (which is very good) around £10 a bottle - so everyone gets half a bottle. Food is pasta and pizza, and is excellent.
RSVP to David Murray [david.murray@bbc.co.uk]