This site will give you loads of advice.
http://www.landscapejuicenetwork.com
Paul Power's book 'How to start and run your own Gardening business' - marvellous stuff, can order of Amazon.
Your biggest problem is getting enough work to last you through the winter.
You will never make a living charging £10 per hour the average is £15, this is if you do it legit, eg Public liability, Waste transfer license, Ni, Tax etc.
My mower for example costs over a grand (not a ride on) that cost me £4K, then you need strimmers. chainsaw, blower etc etc....oh and a van.
Plus chainsaw certificate