Its not the flight training that is a problem, that only requires 15hrs and the flight test. It is the ground school. If you dedicate yourself to it expect to take a minimum of 6 months for the IR theory. This covers the 300hrs of mandatory distance learning, and the 10% mandatory classroom followed by the 7 exams.
I have been working with the CAA as part of an AOPA/PPLIR working group for nearly a year on streamlining the IR process. But at this moment the figures above are the minima you should expect.