Hanging kitchen wall cabinets in a new extension - what fixings to use?

[ReallyRatherNerdy]

We have just taken delivery of our new DIY-Kitchens kitchen units. We're fitting them ourselves. It's a new extension with two layers of insulated plasterboard on top of the studs. The builder told DH to use a particular kind of fixing with a really coarse thread that would grip well into the plaster board and insulation. Apparently that type of fixing is not enough in a single layer of plasterboard, but because we've got two layers it will grip enough.

DH is a bit of a worrier and is fretting that won't be enough to stop the cupboards falling off the wall when they're filled with plates.

Does anyone have stories of fixing cabinets to a similar type of wall and can confirm they stay up? You would help his peace of mind, which means we could actually get on and start hanging them rather than searching the web for info on fixings.

one tip i wouldnt put heavy crockery plates in wall cupboards when our lovely new kitchen went in i did this put the denby dinner service in a top cupboard and within a week the cupboard was visibly bowing so i moved it all to a base cupboard which has a sturdier shelf

cant help with the brackets as our house is 1940's brick built

Bit late now for you, but for others planning a kitchen, we fixed extra battens to the bricks behind the new plasterboard wherever we would need to put cupboard fixings.
Given where you are with this, though, in one place where we had to fix a cooker hood not where anticipated, we used these https://www.geefix.com/
Expensive but they do seem to be pretty strong, and say they can be used on insulated board; they worked fine on ours. You may need to check that the overall depth of your board/insulation would be OK. Won't go where there is a batten, but if there is a batten, you could just use long screws, even right back into the brick behind the batten as well, if there is brick there. The sort of screw that you drill a hole, then hammer in the screw along with it's rawlplug.

Thanks both
Issey that had happened with our old kitchen cupboards so when we designed the new one we made sure there was a low cupboard for plates!
Blue our problem is there's no void behind the plasterboard, rather it's filled with insulation - kind of a solid block of foam with a foil backing, Selatex, I think.
Anyhow a local builder's supplier kindly sold us 16 out of a box of 100 hollow-wall anchors that look like these, plus a gadget that you use to squeeze the metal wingsout into a sort of umbrella behind the plasterboard. We tested it on an offcut of the insulation and it should work. DH found videos of big builder guys hanging off them, so is feeling reassured😊

I love those videos, @ReallyRatherNerdy 😆