Finally something positive to report.
Having concluded that exercise is not helping my AF, I decided to take the plunge and purchase an electric conversion kit for my mountain bike. Since fitting it on Wednesday, I have done 80 miles on it. On Thursday and Friday I went solo in Scotland and rode 2 of the "7 Stanes" mountain bike trails, and today I joined my cycling friends in Northumberland and rode out to watch the National Hill Climb competition.
Whilst I was watching the race today, one guy asked about my bike, and within a minute I discovered he had AF too. Small world!
Of course, I'd much prefer to be riding without a motor, but given my situation, my new eBike is a godsend. I have so missed being on 2 wheels and it feels so good to be back