MSM do road both types of insurance........ Non registered or road registered and know what a trials bike is...........
http://www.msminsurance.co.uk/personal-insurance/motor/motorcycle-trials-enduro
Chain and ground anchor is what the insurance company wants so do that and if it's knicked you claim your money and get another.. Chains will stop the chancers. Won't stop someone who comes prepared.
Do a HPI check at a dealer (Not internet) by vin number. That will give you the registration number. Then you can request a new log book on a V62 form Much cheaper that way or can be free. Simples https://www.gov.uk/government/publications/application-for-a-vehicle-registration-certificate
Doubtful as loads have done memberships and licence renewal since October., Had my new 2019 licence for 6 weeks now........ You best phone them in the morning..
Already available FREE since 2010 via the DVLA. Vin & engine number will go on the DVLA system so if recovered it can be traced......... https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/527473/inf85-protect-your-off-road-vehicle.pdf
Most bikes are checked with a visit when registering now by a firm called SGS on behalf of the DVLA. They check frame & engine number and make sure the bike is original. If no clear and visable numbers they won't accept.