It's legal in the UK to have gear for personal use.
If I remember right, it's illegal to import, export, supply, or purchase. Any of these will get you charged. But for possession, they will just confiscate the gear and give you a caution. Although the amount they deem for personal use is probably different to anyone elses. And if you have them in your possession, then you must have 'found' them or you're guilty of the first set of offences.
On a side note, there was a guy in my old gym who said he bought some gear in Turkey while on holiday, and actually declared it at customs and was allowed through with it. Not sure if that is possible or if he was full of shit. He did wear 80's stripy workout pants and a 'fanny' pack, so I don't think he was all there.