Can I just express a doubt about holding this in Southampton?
There's not much point holding a bash in a big town or a city - it just makes the traffic worse and the prices higher. In addition, both Southampton and Portsmouth can be a bit of a bugger to navigate if there are any traffic problems or big summer events going on ... it's all that water, y'know.
Hampshire has some lovely smaller places which are just as easy to get to, and where our custom may be more welcome to the venue.
Think Winchester, Andover, Alton, etc.
I'm also a bit puzzled at the idea that we might get 10-12 people. Nik's Shoreham bash a few years back attracted more like 30 IIRC.