Stick with it Chris
I'm sure about half way through the Essex Ham course I suddenly started doubting what I thought I already knew!?!
Leave your RSGB past papers and mocks to one side for the moment as it's A) a distraction, and B) Parrot learning.
Enjoy the course because I know that as you near the end your confidence will suddenly boost and you'll feel much better about it all.
Don't fret about it all, they're not looking to test for 'genius', just making sure you'll be a great radio operator
If it helps any, I acknowledged the 'Charing Cross' question as a sort of 'trick' question because although I thought I knew it I missed it on a past mock paper(!) I had that particular question on my RSGB exam.....and it was asked straight out with no deflection or confusing elements whatsoever!
It's only in hindsight that it seemed rather over the top, but if I hadn't learned that question inside out I wouldn't have known the answer either
(Plus you can look it up on your exam reference sheet anyway! It's a test to see if you will either know, or better still, check your operating licence requirements.)
You'll do alright. Just enjoy it.
Best of luck,