A lot of general handymen types that work from home with a van often charge around �25 - �35 an hour in labour, and sometimes add some profit onto the costs of the parts/materials.
If you are skilled and certified enough to do whatever job it is you are looking to do then I would expect you to be adding on �30 an hour in labour.
If you are unskilled and looking to go around sweeping up leaves from peoples gardens for example, you would obviously have to lower your labour costs to around �8 - �10 an hour.
Obviously you could charge more, but it may make you uncompetitive against other people, or charge much less but then your reducing your overall salary.
Obviously the idea of �30 an hour sounds fantastic (30 hrs = �900) but you also have to take into consideration your paying van costs, business costs, possible licence costs, diesal costs, etc etc.