Foz, i'd expect you to be in the £25k band as an unlicenced mechanic depending on what shifts you work. The more depressing the hours the more money you get!
Some places offer a lot less and others pay more. As said above, this rises rapidly once you start certifying your own work.
Contract rates differ , check out the job sites for the hourly rate on offer.
I take home similar money to that mentioned by mrmagooo but work long shifts which is a fair chunk of the pay and have been certifying on many different types for a long time now. Note the wages I mention are gross not take home.
Theres a lot to think about when chasing a potential employer too - if they run a single aircraft type it means that any additional licence pay will be small and your experience will be very limited.
If they run many different types it will broaden your experience and make you more attractive to other employers in the future. My company has over half a dozen different large aircraft types in its fleet at the moment and although we don't get licence pay for each type it is a good thing to have on your cv and licence.
Check also if any potential employer provides type courses for free or whether they require a bond. If you go the contractor route you'll almost certainly end up paying for some of your type courses and they can run into serious ££££.