I'm a bit confused - the only issue now is, regards the cheque,...

I'm a bit confused - the only issue now is, regards the cheque, as the takeover has progressed to mandatory stage. As regards the address, that's a responsibility of the PNA share register - put something in writing to them - [copy it to Boardroom might be a good idea]. Don't call - put it in writing.

Can't you drop a note to place you use to get your mail [live] - with a forwarding address for anything that might turn-up in the next few days?

Ultimately, it's no big deal, so don't be worrying, this stuff goes on all the time!