At the end of every financial year you need to complete a tax return. This can be done online via the HMRC website here.
Housekeep have also partnered up with Taxdoctor who can calculate, complete and submit your tax return, so you don't have to complete it. They gather all the information and complete the tax return for you. They will help with tax deductions for cleaning products, travel costs, and other expenses.
First step is to make sure you have registered yourself as self employed. This is easy to do, just follow the guide here.
Then complete your tax return yourself or contact Taxdoctor for more information on how they can do it for you.