As a Brighton resident for the last 15 years, I think it's only right to pass on some tips for anyone staying over
Travel
By train it's probably going to take around 4 - 4.5 hours from your door to brighton station. From there, get the Lewes train to Falmer. It's usually sectioned off on matchday especially for the fans, so you can't miss the temporary railings.
If you're driving, be aware free parking is virtually non existent in Brighton and has traffic wardens that can sniff out an illegally parked car from a mile away, but there's plenty of car parks
For the extravagant, fly to Gatwick. It's then about 25 minutes by train to Brighton
Accommodation
There's an abundance. However, anything on or very near the seafront is gonna cost.
Drinking
If you want the Yates', Wetherspoons experience, any pub like that is on West St. From Brighton station, walk 5 minutes straight down the road opposite, past the clock tower, and you're there. For any other type of pub, take your pick. There are a lot, and I mean a lot of pubs in Brighton. Expect Northern Quarter prices in most pubs. While most pubs don't ban footie tops. Some do, so be aware.
If I think of anything else, I'll come back and add to this