When we've run (or I've performed at) house concerts in England (and Wales) the usual form is that people invited will have eaten beforehand but the host/ess will provide refreshments, teas and coffees and maybe some alcohol. By all means take a bottle of wine and a cake or some snacks if you would be happier doing that. Normally if there's some other requirement they'll tell you that when they tell you the venue, time and suggested donation. Expect it to be a less formal kind of concert - some time to talk and mingle first of all, then the concert, normally (as in a folk club) in two sets of around 40-50 minutes. Sometimes there are some other singers but not always - they will have been fore-warned. Sometimes there's a session afterwards but not often, in my experience - it's more likely to be a friendly chatting session.
If on the other hand the suggested donation is large enough (over £15) or the event starts early enough (prior to 7:30 pm)there may be more significant food on offer. You really would need to ask in that case to be sure either way.
And I don't know of many circumstances where there could be any serious fox paws involved, especially if it's a first for you. They're normally very friendly evenings and I love playing at them.