Just a word of caution - I’ve used the UK price comparison sites before and been a bit stung. The company I chose (the top result at the time, Grade Mobile) had defaulted to ‘perfect’ condition without giving you the option to change it when requesting the comparison, so basically the quote they provided will be downgraded if your phone is anything other than pristine (my 13P was very good!). You can take their counter offer or ask for your phone back, but their return postage is only minimally insured so it’s risky so you’re kind of stuck…you can make them a counter offer and meet them in the middle which is what I did but I found the whole thing a bit misleading.
Still got a lot more than Apple was offering though!
TLDR; always read the small print! (& go direct where possible!)