Private building control firms, local authority or NHBC building control all work to the same building regulations ,although NHBC have their own additional Standards which they use, and they should all be impartial enforcing the regs.
As DIY says there should be no draughts; in fact there are rules on air penetration and limiting infiltration ( why are building control happy with their side of things if you are getting draughts from under windows, floors and balcony doors !!!).
The ventilation of the room should be controllable by trickle vents (background ventilation) and opening windows (purge or background ventilation) .
Ventilation of the air space on the cold side of the insulation is to reduce the risk of condensation but that should not enter the room as draughts ,as others have explained.
Others have already advised on an independent appraisal but why not speak to building control or the person who drew the plans for the bldg. regs application and mention the problems first ?
Exactly!? And is somewhat of a concern to me..... I will get in touch with them again .... what I'm trying to do with this thread and my research is arm myself with as much info as possible so I can't be fobbed off.... once I mention Part L, C, etc of the Building Regs that should get their attention....
Thanks for yours and all other's replies.