OK that is £4800 on top of your annual earnings what ever they may be.
You are allowed 10% wear and tear and up to 30% on repairs but these last one have to be receipted. Expenses are well written up - legal fees, hse insurance, repairs but not improvements, maintenance, mortgage interest
so let us say that is £1500
so your unearned income is 3 300, and if you pay tax at 20% then your tax bill is £6 60 and if it is 40% £1320.
simples
commonest fault is to charge the whole of your mortgage against tax, and not just the interest element.