There are always going to people who outcast you, judge you, reject you & ostracize you, no matter what your circumstances. That's just the way of the world. I could go on & on about that subject, but I won't because in the end, it still holds true.
All you can do is be the best YOU that you can be right now. Anything you do to improve yourself would be helpful, long mental health record or not. Go to school & take some classes. Learn to paint or play in instrument - do something you've never done before, but always thought about in the back of your mind. Improve yourself, improve your mind. Volunteer somewhere that needs help - a hospital, a nursing home, a church, anywhere that needs help. Even if it's just for an hour or two, for one day or evening a week. You can help someone learn how to read, you could help re-shelve books in a library, the list is almost endless. You will feel so much better about yourself, and other will see you in a different light as well.
I know absolutely nothing about the legalities in the UK. But I'm almost positive that if you start questioning people who DO know about it, that you'll at least find out what exactly it is that you might be facing in trying to move out of the country. The fear of the unknown is great. I'm in the US, and if I wanted, I could call up any attorney in the telephone directory, and ask them a few questions, and they'd let me know what I needed to know. From that point, I would be able to determine if I'd need an attorney to proceed or not. Perhaps your doctor could provide you with information.
I know it's scary to want something & suspect that you'll never be able to have it. It's scarier to actually work on finding out for certain, one way or another, if you'd ever be able to achieve it. But once you do, it's like you've been freed from a prison. There's probably 3 directions that information could take you at this point. One would be the answer of a flat out "NO", telling you that you cannot now or ever in the future leave the country & enter another. In which case you would have to re-evaluate your life, setting your sites on another dream perhaps. The second direction would be "YES", you can go, just get a passport & whatever else is required to leave a country & go to live in another permanently. The third direction that finding out what is possible could take is possibly get something on paper from your doctor, stating that you've been under his care for X number of years & are doing well (not saying you're cured, but that under medication you're not a threat to yourself or anyone else). If something like that is possible, then it is something that may take a while, but definitely worth working towards. And so that gives you the 3 choices of yes, no, or maybe so. And knowing where you stand is so much easier on you than staying in the dark and never knowing.
Now I've got some questions for you - is there no privacy law protecting someone who is diagnosed with mental health issues there? Is there a stamp on you or do you have to wear an ID that marks you as someone with mental problems? Do you have to notify neighbors within a certain radius of your home, to let them know what problems you have? Are you limited to only a handful of possible jobs because you've had mental health problems before? Did you take counseling or therapy or a class to get your rage issues under control? Do you refresh yourself on that information on a regular basis to help prevent a relapse? Do you check in with a counselor/therapist/instructor every so often, to see if there's any new ways to handle your anger? Whatever your problems are, there are almost always ways they can be dealt with to minimize them, making you an acceptable member of society.
I guess what I'm trying to say here, is that unless you go out of your way to tell people about your problems/issues, most of them won't be aware of them at all. If you are still living where you were when the problems began, then the people there (if it's a small place) will probably always remember that you were the one that lost control & screamed someone down in the middle of a shop. Or worse; I'm just trying to make a point. People will remember the bad things much longer than good things. And they're always quick to point it out to you, too. It might be better if you moved a couple hundred miles (kilometers?) away and start a new life where no one knows you.
And don't worry about how people perceive you, wherever you are. Just keep on being the best that you can be now, & don't give anyone anymore reason to talk about you behind your back than they already have. Oh my, I seem to have written a novel here. Apologies, but I meant well.