Visit your local flying schools, and ask. I had an expired 1964 PPL, and retrained as required for a lifetime PPL in 1987. I've kept current since, and now have a National PPL and an EASA PPL.
Consider an EASA LAPL or, as suggested, Microlight Licence.
PS If you can afford it, you'll only get accurate information from a lawyer specialising in EASA and UK Aviation Law.