battens behind d&d plasterboard

[scfc151]

forgive me if this sounds a stupid question.
in my extension with thermalite block its gona be d&d with 12.5mm board
i was gona put some battens on the wall for fixing rads and tv brackets to under the board
the electrician has used 25mm back boxes. I was going to use 25mm plywood underneath.
will this cause any issues with 2nd fixing faceplates. obviously the backbox would only come to the back of the 12.5mm plasterboard

cheers

 

[23vc]

Nothing wrong with fixing some 2x1 battens behind, just make sure they’re plumb. If it’s a small wall I’d just batten the lot and no need for dabbing, just done exactly that in a bathroom.
Not sure what you mean about ply and knockout boxes.