Where do I get books?
Note: I am not affiliated with any of the shops mentioned below. Here is described solely my bookish experience.
Physical books
I was studying in the UK from 2016 to 2019 and, of course, it was a must for me to find a book shop. And I found Waterstones in Liverpool. It is absolutely fantastic shop with a cafe inside and free places to sit while you choosing the right book. It offers all genres for taste from history books to fantasy, from educational books to horror, from classics to YA.
These websites for ordering books I use when I am located outside the English-speaking country for more than one month. They offer both a great amount of books to fit every taste. Moreover, they offer free delivery, however it is not traceable. So far I have not experienced any problems with them. Books were delivered in a good condition and in time. The last time I ordered from them were "SAO: Fairy Dance" all three books.
During my stays in Latvia I go to Polaris that has a rich collection of Russian books on any topic, if I am visiting Riga by any chance I go straight to a Globuss shop that has a substantial bunch of English books on offer.
Library
Everyone forgets about library when you can't go to a shop or you are out of books on shelf. Honestly, I haven't been there like for at least two years now. But it is a good reminder for me to visit it if I run out of books.
E-Books
Litres is a humongous collection of physical and ebooks. It is my main source of electronic books in Russian language. The app and website quite often has discounts varied from 20%-50% on the ebooks. Also if you google you will be able to find variety of promocodes which offer one free book each from a given list. Unfortunately, it offers very limited amount of books in English.
As for English books I haven't purchased any ebooks yet. But I might do in the future.