How much Tax and National Insurance Contributions do I pay I want to work out the percentage for this year?

There is a calculator on direct.gov.uk. Self Employed gets complex with types of NI contributions and expenses.

Based on those figures you will liable to tax at the basic rate. That means that your self employed profits will be taxed at 20%. Your profits are your income (say £17,000) less any expenses you incur earning that money. If you do this at home, you can claim a small amount for using electricity at home - say £3 per week unless you want to keep very accurate records and apportion the costs to get an exact amount. If you have a dedicated study that you only use for business you could claim a bit more. You would be best to engage an accountant to help you start up and deal with your first year. Once you get the hang of it you can do it yourself. There is plenty of guidance available online. You will also pay 2 types of NIC. Class 4 NIC is based on your profits and you pay 9% on your earnings over £7225 (£7665 from April). This is added to your tax bill and you pay it with the tax. There is also Class 2 NIC which is a flat rate £2.50 per week (£2.65 from April). So, as well as your normal tax and NIC on your salary you will pay:- Tax £3400 NIC4 £879 NIC2 £130