Thanx for the replies.

I am only going to use the puller radiator fans and not the radiators like the product below.

https://www.ebay.co.uk/itm/16-INCH-SLIM-ELECTRIC-RADIATOR-FAN-PUSHER-PULLER-120W-HIGH-POWER-MOTOR-3000-CFM-/231589876967?hash=item35ebd514e7:g:-3QAAOSw1vlUundL

These fans can easily be attached through the louvres of the vents to draw air in to the cabin

so far i am looking at the temp controller below but would really like a variable voltage output to control the fans so still looking

https://www.ebay.co.uk/itm/ITC-100VH-Digital-Pid-Temperature-Controller-220V-heater-k-sensor-cooling-SSR/322461862670?hash=item4b14398b0e:m:mxHX7fZDpXDcd

Reason for 12v is because they are cheap and i have plenty of spare server psus to power fans