One item which crops up & could mean an MOT failure is the fuel cap!
If you look inside the cap itself you’ll see a sealing o-ring, the photo on the left shows the seal which has degraded over time with the photo on the right showing a new cap with seal fully intact. For the sake of a few quid, unscrew your cap and have a peek at your seal.
If you notice your cap is looking like the photo on the left….then get it looking like the one on the right! You’ll also get a new retaining cord.