What can I claim back tax on?

Can anyone tell me what I am entitled to claim tax back on? I have never claimed for anything and i think its about time i do. I work full time, have one child but no partner. I have recently just bought a house under the "Deposit to buy scheme". I get my maintenance from my childs father and i get child benefit. As far as Im aware i dont qualify for "one parent family allowance" or medical card or anything. As everyone knows, times are tough at the moment and every penny means something so id be grateful if anyone could tell me if there is anything else i should be looking for or claiming tax on.

Check your cert of tax credits to see that you are receiving the correct tax credits.

e.g.

refuse charges paid
trade union fees
rent paid
lone parent tax credit

etc.