Your first decision has to be 'regular' insurance or 'classic'. Classic works well with a restricted mileage and you should be able to get an 'agreed value' included BUT you will not build a no claims bonus.
I too use Peter Best with a classic insurance and am very happy with the service. To obtain the biggest discount you need to be a car club member.
Richard
1.8i Mk2 Solar Red, 16 inch square spoke wheels, MGFMania hood with zip-in glass rear window, DRLs, Kmaps ECU, Pipercross panel air filter, MGOC Supersports back box & some cockpit bling