Scared to travel alone, any tips?

I have wanted to travel alone for a while now, and I am seriously considering doing it this summer holiday. I want to travel to the UK (if it's possible again), because I speak English pretty well, and for my first trip alone, I want to be able to communicate well.

However, I'm scared to do it. Not because I am a women and I'm scared something might happen to me, but I'm scared that I'll feel lonely at some point, and not be able to do anything about it. For some people, travelling alone is very fun, because they enjoy being alone, or they are very social and make new friends easily. I do enjoy being alone, but I also get this feeling of loneliness very easily. I don't think I'm very socially capable, but I would like to make new friends. I have avoidant personality disorder. One of the symptoms I have is that I'm afraid of judgement and I go out of my way to avoid it. I don't think I have a severe case of it, but it does prevent me from doing certain things, like talking to strangers. I'm afraid that I'll say or do something wrong, so I tend to stay quiet. At home, I avoid going outside as well, because I'm scared that people will think something bad when they see me. Eventhough I have these troubles, I would like to travel on my own. I think it would help me grow.

So, I would like to ask if anyone has tips for me. I don't think I want a travel buddy for the whole trip, but meeting new people at the location I'm at would be nice. How do I do this? And are there any tips for me for travelling on my own in general? Are there things I should know when travelling to the UK?