I've just ordered and fitted the OBD lock, delivered for £104 in the end, I forgot to ask for Matt!
Very easy to fit, as simple as push the lock over the port, screw the 4 screws into the port using the provided driver and key.
keep the driver at 90degree to the screws or it can start to tilt over forcing the key out/off the screw head.
Very pleased it was that simple and feel just a little bit easier leaving the car.
Biggest concern was to sticker the window or not, went with the sticker in the end as a deterrent.