Deeege im 22 in June 
Are you really? You've not mentioned that.
I'm a decade older than you and still hoping to see Eminem.
Saw him last at Astoria (is that still open?) in around '97. Before he got big.
You should definitely aim for a hotel, and the train, don't drive down. It'll be just as expensive and you're bound to be over the limit in the morning.
We saw Depech Mode in November at 02, got the premier inn (i think) for about £80...