Will the 4K UHD disc play in my 1080p Blu-ray player?
Depends on how old the player is. Newer machines ( not 4K ) will play them but just not in 4K.
After you buy the 2-disc set (I ordered mine from Universal’s site GRUV and got offered a 20% off first order promo) then you can play the Blu-ray disc that comes in the set, and later, when you eventually upgrade to 4K, that 4K UHD disc will be the one you’ll want to play.
Some 1080p discs have been made from films being scanned in 4K, and you can play those discs in your player too.