Whose home are you working from? You might need permission and/or a treatment license from your council.
You will need to tell your home insurance company too and may need to change companies.
Hmrc need to be informed that you are starting a business.
I would make sure you have a contract in place for your peace of mind, so you agree on how profits are split, how you pay for stock, holidays, if one of you is ill on your day and what happens if one of you doesn't want to do it any more. Especially for the person who doesn't own the house x