The fitting instructions for that unit make no mention of fixing clips. Personally I'd go with the manufacturers fitting instructions as using your initiative can lead to voiding the warranty.
Thanks - ended up just following the instructions. The foam strips seam to have softened into some sort of sticky strip, so that and the weight of the hob are holding it in place pretty firmly.
The fitting instructions for that unit make no mention of fixing clips. Personally I'd go with the manufacturers fitting instructions as using your initiative can lead to voiding the warranty.