Like @George1 I just used the app. Took me a couple of goes too, but eventually it liked my photo… Saved me time and a few Euros!
Overall the process was incredibly quick and efficient. I posted how long it took me to receive mine back when I did it… It was something crazy like 14 days from start to finish (including a bank holiday iirc).
Highly recommend using the app if you’ve got a compatible smartphone.
Edit: crikey, apparently it was 2023 when I renewed mine… Where did the time go? Passport renewal in 5 days - #3 by Gareth