I'm good to fly this day next week!
The bride and my bestie told me yesterday she was a wee bit worried about all this (oops, sorry Kat) but it's all resolved. Now I have a document that is valid until March 27th, 2021. WHOA. I haven't even thought about the 20s!
Also interesting is that this here passport is an ePassport. I've never heard of such a thing! How very high-tech-Bourne Identity-Big Brother of them.
Anyway. One less thing to worry about. Now, fingers crossed that the alterations to my bridesmaid dress that will cost me £30 turn out well...