I HAVE POUNDS LEFT OVER.
I decided to keep them just in case the exchange rate got better. At the time I wasn't hurting for cash, so there was no pressing need to get them changed. Well, they're gonna sure help me out now! Of course I do need to actually get to the post office before it closes to exchange them.
Wow, the things you store away for later that you forget. I am a dang squirrel.
Post office ahoy!
EDIT: To summarize an extremely roundabout and frustrating day, apparently neither the post office nor the bank changes money. (Go figure, the post office in LONDON did it just fine...) And the closest exchange shop is M-F, 9-5. What. Thefuck. I can send Sardonicus on over on Wednesday or something, but by then I'll already be paid!