I would carry on and send him detail on the car, it won't harm anything if you keep personal/bank parts out of it, and many people just want to have some form of confirmation of the cars information as a comeback if anything turns out wrong, as it protects against people hiding behind the pretence that autotrader got it wrong.
Make it clear you require the car to be collected and balance paid in Pounds Sterling, cash upon collection.
If genuine the buyer will be cautious and ask seemingly silly questions, if not you haven't lost anything.