Forget the company im with just now, have a traders policy thats fully comp and only restrictions are that the max value of car i am insured to drive is 20k.

Costs just under 600 quid a year for me and the wife.

Was never asked for proof of being a trader etc, just said i repaired other folks cars and needed insurance to cover me for any vehicle. Am covered for bikes as well so find it a huge saving now as used to have 3 policies on the go at the one time, mine, my wife's and then another one for my bike !