Late getting to attempt this but I quite liked it. It is actually three almost completely separate challenges. First and most fun was solving the clues and identifying the letter values. Simple logic and no need for electronic aids etc. I ignored 19 and 34 - too hard.
Then populate the grid. Again mainly a logic puzzle but you are left with some ambiguities without 19 and 34.
I put a couple of options into factorisation calculators and decided it was not going to be worth the effort so just did letter substitutions for what I had.
Finally identify the set. The pattern dropped out fairly quickly from the top left and I was able to complete the grid without on line factorisation aids.
Not the usual mathematical Listener but an interesting and clever one.
The set members are hard wired into the brains of people of my age - it may not be quite as easy for younger solvers to spot them.