This is from Wiki:
The S-Tune GT was released by NISMO to celebrate its success in motorsport, particularly in the Super GT series. The S-Tune GT featured revised long nose bodywork as in the Type-E, a modified version of the VQ35DE engine called the S1 with more power (300 PS / 221 kW / 296 hp) and higher redline (7200 rpm), as well as a sportier NISMO suspension.
20 were produced each month in Japan. Although Nissan did not officially sell S-Tune in UK, Nissan Motor (GB) Ltd. imported 1 S-Tune GT to UK
So we can tell that if it's a UK car, it's a fake. You're looking for the suspension, exhaust, engine bay, genuine nismo bumpers, which will have a nismo logo in the resin of the bumper itself if you can see down from the engine bay. Dials aren't hard to swap out so aren't conclusive. I'd say the log book is good as you probably wouldn't re register a fake. Nismo alloys end up on everything, so aren't conclusive either.
If you do buy it, chuck those floor mats please