I too do not meet the criteria for the six weeks, but am planning on going to Peterborough tomorrow morning. As far as I can tell from reading online, London don’t have an enquiries queue at Passport office, so they won’t let you speak to anyone (You can only get in if you are collecting passport).
We are due to fly Sunday morning, wedding is on Monday. I think chances aren’t great, but I’m going to give it a go, Ill kick myself if I don’t.
The only acknowledgement I got re upgrade was the automated response saying my date of travel has been noted. I am heartened that no news is good news and I haven’t been refused yet!