I tried to reply to Allan, but I just got a box saying there was some issues with my reply. I hadn't even started! All I wanted to say is if ever your injection is due, and you can't get an appointment, (in your case your Dr. away), you do not have to accept this. There are other Drs. I am OK now, BUT I had the devil's own job getting appointments on time, or at best 2 weeks late.
As I and others have shared on this platform before get the Macular Society involved. Wonderful help/information. macularsociety, Helpline 0300 3030 111. I wish you the very best Allan; getting your GP and MP involved helps too with appointments!