You dont really need an encyclopedia brain full of motoring knowledge to start a business its the business idea and plan which will help you suceed.

Cost of starting a business depends on how big you want to start the location/competition. Say starting a garage in London the rent is going to be a killer, but say out in the sticks it be cheaper with possiblity of getting a better location for your money.

A estimate a decent set of basic tools and equipment will cost £60,000, say £30,000 for rent and proberly another £25,000 a year ontop for other bits like insurane, tax, costs, say £150,000 to start up a 1 man band.

Getting investment aint easy most businesses start by putting thier own money into it, investing it and after a substantial amount banks and that are more likey to help you as your putting in your own risk.

Personally i would start of as a specialist in a hand full of areas, build a rep in that arena an then branch out instead of going all in trying to offer everything it can eassily turn out too much for you to manage.