If you go to Dorset, then you could try the Charmouth Heritage Centre or the Lyme Regis Museum. Lyme should have quite a few guided walks available. I’m not familiar with the locations nearer to you but you could try UKAFH. If you don’t need a tour then you could try Abbey Wood, in South East London or the Isle of Sheppey in Kent. The locations guide in the UK fossils network should give you an idea about places you could go to. Depends what fossils you’re after.