I look to take £40-50 an hour - however 30p in every pound comes to me directly as a wage and the rest 70p go to the business for supplies, new equipment, insurance, marketing all that type of thing.
So if your talking actually earning £30 an hour id need to be taking about £100 an hour.
So all those bragging about how much they "earn" an hour you really need to take a step back and work out your costs first.