So I clarified the Jet2 insurance re FCDO, which is basically relates to the policy itself in that:
a) If the FCDO advises against travel to your destination but Jet2/you can and do still travel, all elements of the policy are valid.
b) If the FCDO advises against travel and Jet2 cancel your holiday, all elements of the policy are void – you cannot claim for the cost of the holiday any more than you could claim for damage to your phone by the pool for example.
In the case of b) the options to get the cost of your holiday back resort to the airline – Jet2 in this case – either refunding or rebooking your holiday to a later date. To date then, Jet2 have a good history on this basis of refund and rebooking, but of course there’s always a risk.