Next instruction: 'turn left just before you see the church'.

You'll have to through-ventilate systematically under the ply baseboard. In and out gets easier if your vent space is actually cross-battened, so air can flow sideways as well as upways. Can't you collect the resultant warmed air?

As foster tom said.

The cladding won't be vapour diffuse, but there will be a gap between the cladding and the timber frame that is ventilated, at at least the bottom, and possibly the top too.

vertical battens alone will work, but as mentioned cross battening will help. You need to see what the cladding company require in terms of fixing battens. Also, providing cavity barriers will be harder with counter battening, its much easier if you only have vertical battens.

Any links to systems you were looking at??

Timber