Wedding venue fallen through due to insurance – help! UK/England

Venue fallen through due to insurance – help!

Really hoping someone can advise. This relates to insurance/weddings in England.

My partner and I are looking to get married in August. We've not long been engaged but need to move quickly as her mother has terminal cancer

We found the perfect venue, a stately home by a lake, near to her parents. They haven't done weddings before but were very accommodating. It sleeps 16 but would allow 50 day guests.

They've just let us know they can no longer be our venue, as their property insurance doesn't allow events. They were very disappointed/surprised by this, but they've not run events before (theyre normally a holiday retreat for large families).

Their insurance didn't suggest an alternative, but surely there must be some additional insurance/a premium we can cover? Any ideas?