Jez give's good advice as far as Sole Trader goes.
Fox, and I'm not being cheeky here, have you ever started your own business?.
In fact, what do you do for a living?. I don't think I've ever seen you post anything on that subject?.
I'll be up front as before, I'm a firefighter and I love my full time job.
I started off my part time business with web dev and PC repairs about a year ago, as I already posted.
As Jez said, Sole Trader aint that difficult to get up and running.
Put the effort in and it should yeild results if you are providing a service that folks will gladly pay for.
To start with, undercut the "usual suspects" locally and take it from there.
Word of mouth is the way most things start in this field, then branch out as you see fit.