I think so. Go to the local council for the actual party and serving of alcohol, then to HMRC for a ruling on homebrew.
I just think the organisational structure of the event will mean that they'll rule it out completely, what with it being a bit more than a "sandwiches and a pint" kind of wake - more of a mini-festival if you like.
But yes, I'd play this one by the book - there is no harm in asking and if they do rule it out, then a few kegs from your local brewery will be a good, cost effective option.
