Posted: 19/06/2015 at 21:58
I've been to several of those in the second list. I live in France and have family in Eastbourne and East Sussex, but it's a bit of a drive from London.
Paradise Park in Newhaven is big and has a huge selection of seeds. It has a big selection of clematis and climbers, also perennials. In fact mostly what you'd expect from a big garden Centre. I love places like Merriments and Marchants Hardy Plants, but they are more for perennials. They both have lovely gardens open to the Public, worth a visit for that.