Hope it works out well for you, should be a cracking game.
I used to go over for weekends years ago but it was costing me upwards for 500euro a pop, yikes!
I presume you are flying from Dublin? If you are you can usually get good deals on BMI whose cheap fares last a little longer that Aer lingus.
If you get an early flight say 8am or such you can be in central london by 9.30am, have some brekkie and do a bit of shopping too. Head to the ground around 1pm, have a few pints before, recommend 'The Auld Triangle', head to game at 3pm. Get out of ground by 5pm, few more pints in the vicinity, head off around 6.30 / 7pm for airport. You'll already be checked from Dublin, so no need to check in, just security, jump on your plane at 8 /8.30pm or later. Land in DUB at 9.30pm, no luggage, walk straight out to taxi, home by 10pm, Match of the Day at 10.30pm bobs your uncle.