You've done everything that I'd have done in the same situation.
Good ouck with everything tomorrow and please report back with details of how you got on.
In case it's worth reminding BA of this clause from the conditions of carriage tomorrow...
3c4) If you need to change any aspect of yourtransportation because of events beyond your control, you must contact us as soon as possible. Wewill use reasonable efforts to transport you to yournext stopover or final destination, without re-calculating the fare.
Edit: worth talking to your travel insurer too?