I would suggest you subby for a while, starting your own co is not that easy if you dont have a regular income the bank will repossess your house. The mistake most people make in this industry when it comes to insurance is that the think public/employee liability is enough, you need efficacy. Look at the NSI and SSAIB websites for approval you need a minimum of 5 installs contracted. I would recommend NSI silver as there are fewer Silvers than there are SSAIB co's out there it may give you the edge over your local competition. Its easier to buy an established company than trying to start your own, if you have the guts. I have seen loads of one man bands go under recently only to resurface as employees, the domestic market is getting killed off by the likes of Nest ect and the Commercial market will want approved in most cases because of their insurance requirements. Oh and dont try to win deals on price, the big boys get wind that you are under cutting them all the time they can afford to work at a loss till you are under, sell at a fair price win the deal on best value.