Sam,
Your net pay at LGW will vary between GBP1200 upto GBP1800 a month dependant on your roster. The most I have taken was GBP2200 but that was with other payments which we hopefully wont be getting again very soon, but that is another story.
There are alot of crew at LGW who "commute" from brighton and it is manageable but for an easier life I would definitely recommend getting yourself some wheels.