6mm cable, surface mounted or alongside insulation?

[Super_Paulie]

hi guys.
About to start a stud wall in the kitchen which i intend to pack with 100mm slabs, ply over and bobs your uncle.

However, am i better off running the 6mm for the oven (far left) surface mounted up behind the oven to the connection plate, so i dont have to de-rate it if it was to come up on the inside of the wall and therefore in contact with the rockwool? The oven will be full height so surface mounted behind wont be an issue.

Cheers