If you can get yourself onto a site where you can bang the tiles on all day long, you can earn a fair bit. I know tilers here in the midlands that are earning 200+ per day, but they really are grafting an 8-10 hour 6 day week.
It sounds appealing, but I also like to have a bit of a life too, so I limit myself to what I want to earn in a week (Mon-Fri). Otherwise, you can get greedy and work yourself into the ground.
The work is definately there, and providing your good and quick, then 25k per year is not unrealistic.
Be aware though, that a lot of '4 day tilers' are coming into the scene, underquoting people with stupid prices (and I am talking £8 psm - and thats gospel!) to get the work. They then land on site working out the back of their Ford Mondeo, balls the job up and run off to the next job with the dough, leaving the customer in tatters and then paying somebody decent to put it right.
First impression is a big thing to getting the work - nice cards, decent van, knowing what your talking about and turning up on time for the quote, clean and well presented; not like you have just had a tub of PTB tipped over you and smelling like an ashtray.
Good luck mate