MED.A.030(c)
Applicants for and holders of a private pilot licence (PPL), a sailplane pilot licence (SPL) or a balloon pilot licence (BPL) shall hold at least a Class 2 medical certificate.
As Mach Jump said, the PPL does not include the privileges of a LAPL, unlike the CPL and ATPL, and, even if it did, you could not exercise those privileges unless you held the applicable medical certificate (i.e. at least a Class 2). Unless the UK CAA has sought derogation under Article 14(6) of the Basic Regulation (and I'm pretty sure that it has not) either the AME or the CAA Medical Department has got it wrong.