My next holiday in London

Hi, everybody! I'm going to visit London this summer for the first time in my life! I'm very excited! I've never been in Great Britain before and I hope I'll enjoy it a lot! I'm going to visit London with two friends of mine and with my boyfriend. I'm fond of literature and I'd like to visit historical places linked to famous writers.. I'd like to visit Harry Potter's studios, too..

Hi, Giulia! Your English is very impressive! I'm visiting Great Britian for the first time, too! I'm going with my husband this summer and we're hoping to see the Harry Potter studio :) Should be fun!

My next holiday in London

Hi everybody! This summer I'm going to visit London this summer for the first time in my life.! I'm very excited! I've never been in to Great Britain before and I hope I'll really enjoy it. a lot! I'm going to visit London with two friends of mine and with my boyfriend. I'm fond of literature and I'd like to visit historical historic places linked to with famous writers.. I'd like to visit the Harry Potter's studios too..

This was already an excellent piece of writing. There was no doubt whatsoever about what you meant, and so it did its job. The changes I made are mainly suggestions to improve the style by removing superfluous words and punctuation, and the use of more commonplace expressions.

The only "mistakes" were the use of "historical" and "Harry Potter's". Best to look up historical and historic in a dictionary to see the difference. The studios aren't owned or used by Harry Potter so the possessive apostrophe makes no sense. 

I hope you have a wonderful holiday.