It is confusing at first.
Yes what XW5 said, your earnings, accounts, 'address', etc are public knowledge.
Anyone can look them up for free.
Companies House stores them.
I agree a reasonable consult with an accountant, look, learn, then
possibly head for self-assesment once you know the ropes.
HMRC are very helpful and you can speak to them as
long as you like the phone while on that learning process.