Urgent book suggestion

I'm doing a project for Uni and I need book suggestions that fit the following criteria:
– the book should be at least 200 pages long
(I have like a month for this project so please don't recommend anything above 300)
– the author needs to be born/from the UK or USA
– the book needs to be from the year 1975 or younger (rest of 80s, 90s, 2000s…)
– it needs to have 'serious themes', be a 'proper work', can't be a cheap romance, it can be political, law related, psychological, about social issues, struggles, slice of life, etc.

Wrote this in a hurry, sorry if it sounds all over the place.
Thank you.