Since you are in the UK, why not browse the meet-up groups? There must be some groups in your area that you can join in and have some fun or do something interesting.
In the meantime, start thinking about what you enjoy and how you might be able to incorporate that back into your life.
Or, take an adult education class somewhere - you will get something out of it and might meet people - though I wouldn't count on it too much for the social aspect. Actually, many times after class there is a pub drink so that's something social.
