OL - as far as I'm aware, there is no credit towards the TMG Rating requirements allowable for military training other than 10% of your PIC time to a maximum of 10 hours.
If you have been presented with an EFT partial course completion certificate (annotated with a Yellow Border) you will be credited only the elements completed during EFT training. You will be required to complete the outstanding elements to qualify for licence issue. You will indeed be given credit for the PPL(A) skill test - but only for a period of 24 months from the date of the Final Handling Test.
You have 2 options:
1. Complete PPL(A) requirements on SEP aeroplanes, including the Q X-C on an SEP aeroplane. You will need to prove that you can plan and fly a dual navigation exercise before anyone will let you fly a Q X-C solo! Once you have completed all PPL(A) SEP requirements, you could then do some TMG training and take the TMG Class Rating Skill Test.
2. Receive JAR TMG dual and solo training on TMGs, including the Q X-C on a TMG. Then add a SEP Class Rating later.
You cannot complete part-SEP and part-TMG training for a PPL(A) - it has to be one or the other.
Your cheapest option would be to finish your PPL(A) requirements first on SEP Class aeroplanes at a RAFFCA club. Then do some TMG training and take the TMG Class Rating Skill Test. When you have a licence with both ratings, you will be able to keep both valid with hours flown on either class - which can work out substantially cheaper than revalidating on SEP Class aeroplanes.
Uncle Ginsters, I'm not suggesting for a moment that anyone should use a Dalton in flight for PPL navigation. God knows how you deduced that.... What I am saying is that some ex-EFT folk haven't even been able to use a navigation computer to plan a simple navigation flight on the ground! They have assumed still-air IAS = planned GS and only applied MDR to the track to obtain the heading. That is insufficiently accurate - unless you happen to be flying on a still-air day!