Before you are given a Training Exemption to train on these aircraft, the CAA require a training schedule from you or the Chief Pilot/Chief Instructor detailing what you plan to do. If they agree and this depends on your background, previous etc, then they give you a Training Exemption...For an ex-military guy trained on similar types, the requirements are minimal. For a fresh civvie PPLer, expect to do lots of flying.
Either speak to the GA Dept who regulate the aircraft under CAP632, or FCL who dish out the License Exemptions after liasing with GA Dept.
It is no good being 'checked out' by a PPL with a hundred hours on it.
In my experience, unless they have a proven background on similar types and are exceptional, then a civvie PPL with a 100 hrs on type will not even be considered for the job of checking you out by the CAA. Remember, the Training exemtion issued by the CAA details who can train you, it's not just anyone who can do it!