I wouldn't buy this sort of policy. What I would buy, however, is a policy that would reimburse some of the initial outlay involved in pursuing the fATPL (CPL+IR) in the event of losing a med cat at some point during the long process of getting a professional civvy licence.
Most insurance policies I investigated would only compensate you for the loss of flying pay you were already in receipt of. There is a substantial uninsured risk for anyone looking to invest up to £100k for a licence, and they may never get to the point where they earn flying pay (indeed - some even continue to pay to fly after they get their first job).
It would seem a fairly simple policy to set up. Applicant gets class 1 medical. Pays premium. In the event that any future medicals is no longer class 1, insurance pays out specified receipted actuals for flying training up to that date. Simples. I'd pay a reasonble premium for something like that.