No - you're wrong. So is whoever you claim to have 'advised you' at the CAA.
The 'Skill Test' which you must pass is the SEP Class Rating renewal Proficiency Check, NOT the PPL Skill Test.
The difference between 'less than 5 years' and 'more than 5 years' is that for SEP Ratings lapsed by more than 5 years, the form in your licence must be completed by the CAA, whereas for ratings lapsed by less than 5 years the form may be completed by the examiner. Unless, that is, you're applying for a NPPL with SEP aircraft rating based upon a lapsed PPL, rather than a UK or JAR-FCL PPL SEP Class Rating renewal.