There are a few options but flights won't be the cheapest as you are playing in the middle of the school holidays.
Check out Ryanair from Liverpool to Girona. Girona is convenient for Barcelona (bus from airport), Perpignan (1 hour drive on cheap but not busy toll road or train) and, if making a week of it, Costa Brava coast (tends to be cheaper than France). I would also recommend at least 2 nights in Girona itself, has a very nice old town, plenty of med style cafe bars and 3 Irish bars with sky sports.
You can get transfers with the travel companies for the day of the match, hire a car (will be expensive in July) or get a train which are cheap and reliable here.