Where to get specific advice for retrofitting insulation

Doozergirl

Remember that the roof is where you will lose most of your heat from.  

Current regs are 125mm of solid insulation in a roof.  That's a minimum standard.  Yes, anything is an improvement but materials and labour are expensive.  Builders deal with insulating loft conversions to building regulations standards day in and day out, it isn't so complicated. 

Your budget has a part to play here.  With a proper retrofit with airtightness taking a part then I agree that you will want drawings to help with junctions etc but there's a middle ground with just an adequately insulated upper floor that comes close to regs, rather than using insulated plasterboard and trying to locate the joists to attach to.  

Doozergirl

Edited.  😂