Anyway…

That’s not to say everyone in the UK knows every first part of the post code off by heart mind. Same way that most US residents likely couldn’t tell you where a random zip code was without looking it up - you get used to the ones in your local area but not generally any outside that unless you spend some time elsewhere enough to warrant it.

You might want to use secede instead.

I just have to add 20 on to get mine, so not too bad.