ZAPTAX will do this for you based on your answers to its questions. Once you've answered the questions to customise your return to your situation, you then fill in the boxes in the relevant sections. Leave blank any boxes that don't apply to you.
Follow the easy guide FAQ: "How do I use the app?" or via the Help section on the app Main Menu.
When you reach the section that shows "Tax Calculation Summary" this will show you the "Total Tax and Charges Due" which is your total tax liability based on your income and allowable expenses and deductions for the tax year. Scroll down to the bottom of that section and you will see the first payment on account for 2015. To find the exact amount you need to pay by 31st Jan, you will need to contact HMRC to check your payments on account balance.