Ciao Ciccia. I think your English is good. Much better than my Italian anyway!
I think the best way to learn a language is to use it as often as you can. If you can get hold of English newspapers that's great, or read news stories on line:
http://www.guardian.co.uk
http://www.bbc.co.uk
The BBC website also has some Learn Enlish pages:
http://www.bbc.co.uk/worldservice/learningenglish/index.shtml
If you have friends who are also learning English you could agree to speak English some of the time, like an hour a day, or all day on Saturday or something.
Shakespeare and Blake are good classic literature, but you want something more modern try Zizou Corder or Malorie Blackman (2 of my daughter's favourites).
If you want to visit the UK that would be a great opportunity to practice your English, but I don't know whether you are talking about coming alone, with friends or with your family.
If you're coming alone, there are some companies that arrange host families for young students in the summer holidays, but I have no idea whether they are any good. If you are going to do this make sure you get a personal recommendation from someone you know.
As you are 14, you are old enough to stay in youth hostels here in the UK, so if you were coming with a group of friends that would be an option. It's very cheap, and they are usually in nice places.
If you are coming with your family there are lots of options, so post a question asking for recommendations for places to stay.
Good luck and have fun!