There is not an edition that is 'illustrated' by Tolkien. All the sets have some of his illustrations such as the Gates of Moria and some have Pages from the book of Mazarbul. If your husband is interested in Tolkien's illustrations for the Lord of the Rings, then get him a copy of The Art of The Lord of the Rings by Hammond and Scull instead https://www.amazon.com/Art-Lord-Rings-J-R-R-Tolkien/dp/0544636341/ref=sr_1_7?crid=3EQD30HXPUS00&dchild=1&keywords=art+of+the+lord+of+the+rings&qid=1608549469&sprefix=art+of+the+lord%2Caps%2C242&sr=8-7
Well you have a few options, if you are starting out fairly new to the bigger world of Tolkien then go for the wonderful books 'The Art of the Hobbit' and 'The Art of the Lord of the Rings' both edited and introduced by Wayne Hammond & Christina Scull. If you are not aware of them they are a very dedicate pair who have worked wonders to expand the world of Middle-earth. Followed by 'Artist and Illustrator' again from Hammond & Scull. You should find those immensely informative and maybe quite a revelation that Tolkien was a superb illustrator.
https://www.amazon.com/Art-Lord-Rings-J-R-R-Tolkien/dp/0544636341
The links are all to Amazon US but you will if you shop around on marketplace or eBay find them cheaper.
The Hobbit and Rings books are both slipcased and are superbly put together.
The Art of The Lord of the Rings by J.R.R. Tolkien https://www.amazon.com/dp/0544636341/ref=cm_sw_r_cp_api_glt_fabc_KCESP24NM430Z017CWXQ?_encoding=UTF8&psc=1