To be completely legit......
First you need to have all of your pants modified with larger pocket openings so its easier for the Federal, State, County, and Municipal governments to slide money out of your pocket.
After that buy lots (I mean lots) of ink pens, paper, and printer ink so you can produce, reproduce, and renew salvo after salvo of paper work to said government folks.
Maintain a comprehensive inventory of your equipment, not because of accountability, but so that it can all be taxed as many times as they can get away with.
Buy a truck that needs a DOT number and then follow the same rules that apply to professional truck drivers. Never work more than 14 hours a day (includes driving time) or 60 hours a week.
Look for insurance and get stiffed by multiple vendors who won't return your call until you finally find one. Pay them lots of money.
Get a quote on workman's comp, have a mild heart attack, and continue on.
This is just the beginning......
As far as learning, even after you are on your own I reccommend maintaining access to wiser more experienced tree guys should you need it. I am not afraid to call some folks for help.....especially when they have 30 years experience. Thats the easy part, the pain of running a small business on the other hand sucks some times.
I see you're in the UK, probably just as complex, except with tea and royalty.