AFAIK on most if not all classic policies you don't get NCB?
Can't advise you on which company etc. sorry.
I would say that doing the following could save you some money:
-limited milage
-Not driving in rush hour times
-there's a company called 'marmalade' or something that means you can only drive for 6am till 11pm quite a bit cheaper i've heard
-When you pass do pass plus - dunno how much it is now but IIRC it saves 40% for first 2 years on your first policy
-After that there are safe driving oganisations such as the 'institute of advanced motorists' that teach you some great stuff and make you a better driver, aswell as having their own insurance scheme for IAM members. I've done it and it was the best use of £80 i could imagine when it comes to driving. (but they won't insure me due to being 19 and wanting to insure a 2L) But other companies recognise it and give discounts. RoSPA is another organisation i think.
-Locked garage if you have one
-no mods (declare them if you have them tho!)
-I did think about getting a tracker, few hundred quid but the online quotes showed i would make my money back in 1 year
Hope that helps!
edit: apparently you COULD set up your own insurance company if you had £1M

lol