yeah just stick membrane on the walls frame up with cls batons from wickes or similar then put either 50mm celotex/kingspan in the gaps or rockwool/standard loft insulation depending on how well insulated you want it, then board, by doing this way you will lose 75mm from the room

so if i used that membrane I could pack the gap between board and block with rockwoool/kingspan and there would be no transfer of dampness through?

If I was going to timber frame it I was just goign to DPC behind the batons etc, but if I can just frame out the walls with the membrane on the block work, fill the gapos with insulation and and work straight off it rather than a gap i'd be happy.

Heating - the garage will be dehumidified, which has a little bit of heating too.

[Edited on 18-02-2016 by AK]

http://www.thermal-economics.co.uk/wp-content/files_mf/1382697243Alreflex1L1DryLiningBrochure.pdf

Although if the inside isn't heated, are you going to notice any difference compared to a garage with sheeted walls and ceiling?

Do it in timber frame

the render will hold back damp but if it was me i would put some breathable membrane on the wall before studs for peace of mind, then fill gaps with either kingspan or loft insulation depending on how well insulated you want it.

this is the membrane i used for my garage conversion

http://www.screwfix.com/p/ybs-roofers-choice-roofers-002-light-breathable-membrane-grey-1mm-x-25m/21912?cm_sp=Search-_-SearchRec-_-Area1&_requestid=98979#_=p

breezeblock with outer render, solid... no cavity

depends on the wall construction as to damp prevention ie

solid or cavity
renedered or breezeblock inner and brick outer

you can also get kingspan or similar backed plasterboard that you dot and dab straight to block work

We're getting another garage built... around 6.5x6.5m with about 3.2m celing height.

I'm wanting to make it a bit more homely than painted brick (breezeblock) walls, so looking onto insulating and boarding it.

Whats the best way to frame, insulated and prevent any damp? I could be massively overthinking this, and prob is just a case of whapping in some backed kingspan between batons and boarding it.