just phone the inland revenue and tell them that you are now working self employed under the name of whatever your calling your self, they will send you a load of gumf till fill in.
if you are employing people then they will send you an employers pack, decide if your going to register for vat (you dont have to untill your turnover reaches somewhere around £60k)
when you phone the inland revenue make an appointment to see one of there advisors and the`ll spend an hour or so going through things like book keeping, your responsibilities, what you have to do and when and whatever else you might be unsure about.
I found it best to do all my own accounts for the first couple of years and just use the inland revenue advisor people (they are free) to check that you`ve done everything correctly before it gets sent off..I found it gave me a good insight into what my accountant now does......................
Basically use the inland revenue they have spent thousands of our money to provide a better service USE IT!!!!!!!!!!!!