The primary issue hurting your aspirations to own a 2015 model Nismo Z34 is the exchange rate, Right now, Z34 nismos are around 5 million yen, which straight-conversion means around £36,000 - already well inside your budget.
This time last year, the same car would have cost you £27,000 - a massive difference. My advice is to either wait until the forex improves or (if you haven't already) enquire at a local Nissan dealership and see if they have ever offered the 370z Nismo in AT.
Good luck either way!