your English is actually quite good, based on what you have written. My parents were Irish, so have a soft spot for the place - but be aware that if you learn English there you are likely to pick up the Irish accent, which is quite distinctive. But each British English speaking territory has its own accent - Australia, New Zealand, South Africa, Scotland.........sometimes it is slight and other times so thick that it is barely understandable, even to a native English speaker from somewhere else.

I don't think we should apologize because our English is not good. It's not our native language. At least we are trying and improving. A lot of English native speaker doesn't know our language at all. At least we know others language. . I have a few friends from Japan who went to Canada and Australia to learn English. According to them, they had a lot of opportunities to speak and practice English but with the non-native speaker. This is because all of their classmates are the non-native speaker. Well.. Only the non-native speaker go abroad to study English. :P They were in Canada, but they didn't really have local friends. Their English only improved a lot after volunteering and stay with the host family in English speaking countries. Like joining Helpex, workaway or WWOOF. If you love British English then just go to UK. Do some volunteering or stay with the host family there. Don't just take English class in language school.

Honestly it doens't matter much. Wendy Monika is right that more people speak American English so you might want to choose that. (We'll see how much role the UK plays globally in the near future though!) I have Chilean friends who have studied in Ireland and haven't picked up any Irish accent at all. Their English still sounds very Chilean. My advice is to go to the place you feel most motivated by. It's also a good idea to consider the cost of living.

I would suggest you to study in America. Why? Because there are more people speaking or learning American English. The UK won't play a big role globally in the near future. Why foreigners learn English? One important factor is to get a better job or to obtain the latest information. As we can see that we will deal with more people spoken American English, not British English.