Hi
I think most will cover you for riding a motorcycle BUT not automatically. You have to request cover and pay an extra premium to make sure you are covered. So you cannot arrange cover online, you will need to phone companies.
I have checked the insureandgo policy details online and with them for you have to request cover. The Travel policies once you have included cover, will cover your medical expenses but not Personal Accident/personal liability. Personal accident which provides compensation for e.g. lost limbs, eyesight and personal liability cover your liablility to 3rd parties in regard to the MC. Personal Accident and Personal liability would come under your motorcycle insurance, so you should make sure you have cover for MC.
Hope this clarifies
Huckster