My mileage limit is 3k per year but i'll up that later probably. That suits me fine as we have 2 cars anyway and we spend most of the time in the Zafira.
As for the conversion, what are you going for? Bear in mind that my car was based on Mark Watts' Astra conversion. My car already had the Courtenay CS5 package fitted which I believe is still in the region of £3600. The listed price for the Astra SC conversion is £5950. That includes the 2.5 inch custom S/S downpipe which i've had fitted too. I've also had the dbilas 4-1 cast manifold fitted with mine. The only mods of mine that were redundant were the airbox and inlet pipe and the EGR cheater as this is required when you have the SC.
The standard conversion without the extra work like mine has had done means that the car will be using standard cams, no head work and standard exhaust manifold. Marks is exactly that and his is still producing between 245-250bhp.
My insurance is thru' Adrian Flux. This is something that I would really look into considering your lack of no-claims entitlement. I was informed that the company that i'm with won't even consider a policy for someone with less than 4 years no-claims.