Everyone who pays tax has the right to file a tax return each year, even if you're 'on the books' for someone and not self employed. Its not really in the governments interest to advertise this fact!!
On it, you are entitled to claim back tax relief on a whole range of things relating to how you get your money to start with; so tools ('capital expenditure'), clothes/uniform, cleaning/laundery, certain parts of travel and subsistence costs, phone calls, materials that you have bought as a part of doing a job (for example if you do something on the side)....the list is fairly long and extensive. BUT - play fair, and do expect that you might get a letter from HMRC asking for some documentation to back up any claims you make.
I am not an accountant and am not offering financial advice. You need to talk to your own.