Classic car insurance policy?

Okay i know there have been hundreds of topics on classic insurance policys but i think this question is slightly different.

First off I'm only 20, 21 in January so will find it hard to find a classic policy anyway (but its not impossible).

For a classic car policy i assume you don't gain no claims, which I'm not to bothered about, but my main question is does a classic policy have to be a second vehicle?

Basically what I'm trying to ask is could i get a classic policy if i currently have a insurance policy in place on my motorbike that i use daily and the classic will be a toy/every so often/heavy rain car. I am also insured on my girlfriends car and often use that but i don't know if that counts towards anything.

Any suggestions?! Could it be done, if so who with?

Got a couple of cars I'm eyeing up, but even for me to be insured on my girlfriends Fiat Panda will cost me £670 and that seems abit steep to me.

An example is I'm looking at a 2.0 Merc 190e and quotes are coming in at about £920 but I'm hoping to get it down a fair chunk! Was also looking at a old 300zx but quotes were something stupid like £2200

Thanks Jack