When you work with Housekeep you are a self-employed contractor.
As a self-employed cleaner, you can choose where and when you work with Housekeep. It also means that you're responsible for paying your own taxes.
If you're self-employed, you'll need to register as self-employed with HMRC. You can do this online here.
Being self-employed means you'll need to keep on top of your earnings and make sure you're aware of how much tax you'll need to pay. This is easy to do and there are online calculators you can use to give yourself an idea how much tax you'd need to pay.
You can find out more about submitting a tax return here: How do I submit a tax return?