My imperfect understanding is that a LAPL implies single engine piston. I thought that if you had an ATPL, you still needed a SEP RATING in order to fly a say, Cessna 150. If you choose to exercise the LAPL privileges of an ATPL, does that bypass the requirement for SEP rating?
For LAPL privileges I don't believe that is the case - you only need to satisfy the experience requirements (including the one hour with an instructor). If you don't have the experience requirements you can "re qualify" for them under the supervision of a flying instructor.
The privileges of your licence will only remain valid if you have completed, in the last 24 months, as pilot of an aeroplane or TMG:
At least 12 hours flight time as PIC, including 12 take-offs and landings; and
Refresher training of at least 1 hour of total flight time with an instructor.
If you do not meet these requirements you will need to:
Complete a proficiency check with an examiner before you exercise the privileges of the licence; or
Complete the additional flight time or take-offs and landings to meet the requirements above, flying dual or solo, under the supervision of an instructor.