I had just this problem and didn't trust the 10mm plasterboard, but I found that I couldn't use expanding toggle-type wall plugs anyway as the plasterboard was held up by dot-and-dab, and there wasn't enough space behind the plasterboard for the expanding toggle-thingies to be inserted. Faced with this problem, I hacked out 3" x 3" holes in the plasterboard where the fixings needed to go, and inserted wooden blocks of an appropriate thickness in the holes. I then fixed these to the wall by rawlplugs and the units to the wall through the wooden blocks too.
Sometime later, I cornered my rother who was arund when the kitchen was installed and asked him how the other units were held up. He said that as far as he knew they were secured only to the plasterboard, so in this case it seems to have been strong enough. I did read in another thread that if you have dot-and-dab then if a lump of it happens to be in the right place then drill through that, the plasterboard will be strengthened in that area. Use you knuckles and ears to find where the dabs are!
Andy.