Houghton Mifflin has put all of the major Tolkien works on sale today (Kindle e-books) for $2.99 each, if you are looking to fill any holes. From The Hobbit through Fall of Gondolin, pretty much everything I checked was on sale. This is a "deal of the day" so prices will go back up at the end of today.

https://amzn.to/2EaHZKX

I checked Amazon UK and there is no similar deal going on there today that I could see.