This caught me the first time - luckily guy behind had no idea where he was so he was glad I got out and had to retrieve wallet from boot - an American who asked if it was the way to Scotland 😂 luckily it was north bound.
I like the m25 anti-clockwise at j8 - you go under the bridge then it is always v fast downhill, slow down to take the m23 exit - lovely.
Also stay on a bit and get the second part of the junction.