This is my local motorway junction, and this prohibited turn has been mentioned quite frequently in the last year. I’m guessing that you went straight on, then turned right at the lights rather than going left in the first place and round.
I note that there was a proposal for a camera to catch/enforce this specific violation. It may well have been implemented now.
I can’t comment on the signage because I’ve been using this junction for so long that I don’t look at it. I think there is a “no right turn” sign on the westbound through road which is relatively new, but in response to people doing - presumably - what you did.
For those unfamiliar, on the east side of the motorway there’s a roundabout into which the westbound motorway exit feeds, plus there’s a road through the middle of the roundabout which is only for traffic going straight on towards Hale or the M56 towards Manchester in the westbound direction (and towards Wilmslow only eastbound). Traffic for the airport environs from Wilmslow has to turn left and follow the roundabout.
If you did what I think you did, I think you’re only going to escape payment on a technicality.
The road layout has not changed for many years, indeed not since the M56 opened I don’t think, but it seems that people turning right when prohibited is either a relatively recent problem or nobody noticed or cared before.
See
https://www.manchestereveningnews.co.uk/news/greater-manchester-news/drivers-could-soon-fined-seven-25009655, for example.
