Steveop - line training is normally done at your home base. You'll normally get your basing options during Type Rating.
MJS23 - when you're type rating you'll be offered a choice of bases, whichever easyjet feel they need cadets to start at. On our TR we were offered Newcastle, Gatwick or Bristol. You then get to choose in seniority order as laid down by CTC.
On the contract you can be moved at 3 months notice and you can't request to change base, you are based where they say you are. In reality you'll stay at the base you're placed at, I only know of once when people were moved.
They do occasionally have base swap opportunities where everyone who wants to change base send their preferences to CTC and if they can do a straight swap they move you, but in reality these don't appear to be that useful and I don't know anyone who has managed to successfully move with a base swap.