Having investigated my annual policy, it would appear i’m covered.
I don’t think I would be covered if they trip gets cancelled, but that is fine. Once i’m there, it seems i’m covered for medical and for being stuck in hospital / quarantine / additional accommodation. Slightly sceptical on that, and will clarify with the insurers before we go.
They did send out a message to annual policy holders that said that this exclusion clause will apply (which is part of the disrupted travel section):
Circumstances known to You before You purchased this insurance or at the time of booking any Trip which could reasonably have been expected to lead to a claim under this section.
But that doesn’t seem to apply to the medical side of things.