Yes, we used Kingspan Century heating engineers and for our full water/heating system exc oil condensing boiler, we paid €19,500 exc VAT for a 3100sq.m dormer.
You got a full diagram showing the lay out, which is detailed in colour for different ducting. The engineer comes out and shows you how to do it, then you lay it all out but don't screw anything together, they come out again, check that it is correct, you then screw all the ductwork together, attached to all the HRV's, Air handling units, temperature controls, etc, luckily I am married to an electrician, the plumber plumbed our solar panels ready for connection to our water. Engineer comes back to check it again for approval and you then attach the plastic sheeting to the walls, ceiling etc to make it air tight. You lay plastic on the floor were needed before the ducting. Then you are given a test for energy rating, he said it is out of 10 down, most people never really achieve better than the 3 mark which is excellent. and then the plasterer comes along, eh voila. 100,000 calories down, 500 strands of hair gone, calluses on your knee's the size of footballs and relief that it is done. Your on the last leg of the journey. We are only starting ours now but that is the proceedure. Anybody that is willing to help you can do this as it is at the end of the day a giant puzzle. My brother in law, who is 17 is helping us, a whizz with diagrams.