Thanks for the advice. Our permits arrived yesterday.
It turns out that their Email response to my initial enquiry went slightly astray - almost certainly my fault as I later found the message in a backup maildrop. We returned our “Annex A” forms and all went quiet again, but on enquiry it turns out that they save them up and issue the permits in a batch.
Our permits are valid for 4th and 5th March. We will aim to go up on Saturday with Sunday available as a backup. Just hoping that both terrestrial and space weather are not too unfavourable.