Just spotted 3 volumes on Amazon Uk for pre-sale, illustrated by Alan Lee.

The Fellowship of the Ring at 464 pages and 19 illustrations.

The Two Towers at 400 pages and 16 illustrations.

The Return of the King at 496 pages and 15 illustrations.

I assume they will be the 50 illustrations included in the Houghton Mifflin edition but the page count seems high at 1360 for the 3 volumes.