I ran a Book Group for my local U3A and still go to one. We all choose a book throughout the year so we read a wide variety of novels and non fiction. Some local libraries have their own groups and will let you borrow multiple copies of books rather then having to buy them.
You will like some books and hate others, but you will read some that you would never have bought and really like.
This month we are reading The Surgeon of Crowthorne, about a man in Broadmoor who helped create the Oxford English Dictionary. I thought I would hate it, but it turned to out to be very good!