I always enjoy Jelly and Ice cream at a party, well it keeps me happy anyway
There are some good places in and around Portsmouth that are available for party hire.
Boathouse No7 in the historic dockyard is actually free if you let them do the catering, which last time I asked was a reasonable £10 a head for a buffet.
They also of course have a bar, and don't have any problems with extended hours.
A completly different idea is Playzone at Cosham.
Don't laugh, they do Adult only evening hire with a bar for parties and corperate events. Obviously all the play equipment is available with I believe a disco in the background.