I would chose a site that has a lot of GA activity. White Waltham, North Weald, there are others.
Without appearing awkwardly freaky, hang around, get to know people, and look to join the club. There are always people, Billy no mates, who have a spare seat, and enjoy taking guys up flying. Share the fuel cost, buy whoever takes you up lunch etc.
Like everything, you have got to make it happen. It won't come to you, but you knew that..