Yes, you'll make more money after hiring a driver. Say you pay ?20 for a one hour job, you'll still make ?30 more than you are now and that's if you don't charge any more than the agency.
Getting a room is obviously more of a financial risk, but incalls are not essential. If you're nervous about putting money in just offer outcalls and see how it goes. I did that for years (and it's not much different now). For me it means that I try to take work whenever it comes up rather than setting working hours, but I do what I want and go to bed when I want so I think it works better than the situation you're in now.
You could also try contacting local ladies and see if any of them would rent their place to you by the hour.
For security, get your own driver. Do the agency drivers need to be available to the agency for the whole shift? That would make things difficult since they won't want to give up the agency job to drive one girl, but maybe they'd be willing to pick up some jobs on their days off. You could also ask on the various message boards if someone knows a driver covering your area, or look on adultwork.
If you don't want to use driver for every job (hotel jobs are the ones where I don't), get yourself a security buddy. Lots of us have offered or you can post your own thread.