If you've committed a crime in Scotland and visiting England?

I am an Irish boy and a few years ago I was really stupid and did something incredibly idiotic. I was living in Scotland and I was in a nightclub really drunk and some guy started a fight with me and the fight got really ugly and we were both covered in blood. The other guy ended up missing a few teeth. We were both taken by the police and a few weeks later I received a letter in the post requesting me to make a court appearance. The letter stated that if I don't appear in court warrent MAY be issued for my arrest. I was really scared and got a flight out of the country the next day and moved to Spain. I have been back to Ireland since but not the UK. Now I am wondering that if I wanted to do something like visit London or Manchester, would I be able to? I think I've really screwed myself but would like the opinion of somebody that knows. Please help me.