It wont actually make any difference to the course what you do during your gap year.
History isnt a vocational course so its not like you will pick up any useful skills. Its an academic course so unless you spend the entire year reading and writing essays, there isnt anything you can do that is actually relevant to the degree.
Work, do some travel, see bits of the world and have some fun. Next summer,read some books and get your head back into academic reading.
Enjoy your gap year.