As you know from doing your exams, anything you spend personally for your business (like the desk, chair, laptop, printer, stationery etc) is debited to the relevant asset or expenses account & credited to your drawings account.
Have a look at www.gov.uk/run-business-from-home.
I also strongly recommend you go to your local branch meetings. They are a valuable source of information. Remember everyone there has been through what you're going through & are happy to help!