I am debating weather to use the Kingspan 8'x 4' sheets or
the Rockwoll roll 100 x 400 to insulate a suspended timber ground
floor.

I have looked on the repsective websites for these manufacture's and
cannot find the answer.
The Kingspan references U-Values but these mean nothing to me!

What would give me the best results bearing in mind the cost
difference per m^2.
Roughly half the price for Rockwool!

Regards,
Rich