Others have already reviewed Barter books, and it is difficult to know what else to add to these reviews.
I’ve known about Barter books for years and it has been on the todo list for as long. This was my first visit and even though I knew it was big, I hadn’t realised just how big is big. You are even given a “plan”:https://www.barterbooks.co.uk/html/About%20Us/Shop%20Plan.php telling you where to find the different categories of books. This is the place to come to find the kind of book you can’t find anywhere else. I had a wonderful time in the Children’s section rereading books I’d enjoyed as a child.
In fact there is something for everyone including serious antiquarian books kept in locked glass cases.
Allow plenty of time for a visit. There is a cafe and comfy chairs with a coal fire. It even has a model railway zooming around the top of the bookshelves.