Wow - some fantastic images on your website!
I'm sure you will work something out....
For a start - I'd suggest checking out a few UK biassed photography forums as well as LL.
A few of the UK forums organise meets and in my experience it's normal to help other members with transport difficulties.
Here's a
recent landscape meet I attended in South Wales; one of them travelled from the South East and B&B'd in Cardiff; there were definitely lift opportunities from Bristol and Cardiff, both of which you can get to easily by train.
That forum also meets closer to London; I just wanted to illustrate an extreme of what is possible
Urban landscapes are very easy for you......
Bath and Oxford are wonderful; and a personal favourite of mine is a day spent wandering around Bristol Docks.
All three are easy to get to for the day by train. Also, Bath and Bristol are positively relaxed after the hustle and bustle of London, a pleasant change from London!
If you have the time and money - then there are some great landscape workshops around that do not need a car to attend.
Here's a fairly extreme example; but it's probably the ultimate UK wilderness landscape workshop.
You can get the overnight sleeper train from London direct to the pick-up point being used by the workshop's boat.