It is all confusing:
If you want to fly a light aircraft, starting today, you can have an EASA SEP, a LAPL and an NPPL SSEA.
After 2015, depending on the type of light aircraft you want to fly, licence requirements differ.
If you wish to fly an EASA Annex 1 aircraft - think Cessna and Piper - then you'll need an EASA licence (so SEP or LAPL).
If you wish to fly a "non-EASA" aircraft, known as Annex 2 - and basically home-built, kit-built, warbirds and microlights - then you can have just an NPPL SSEA or you can use your EASA SEP or LAPL.
If you want a LAPL, you can do it at a few flying schools (according to the CAA) who are basically having it added on to their list of courses free. Or you can - until 2015 at least - do an NPPL SSEA and convert it to a LAPL through "grandfather" rights. I know a few people who have done that, since they own Annex 1 aircraft and so have to have a EASA licence by 2015.
Many people prefer the NPPL SSEA or LAPL because of lower medical requirements - although it is very hard to find a GP willing to do a LAPL medical because of the hoops/paperwork the GP has to do.
Finally, you can get an NPPL Micro and convert it very easily to a NPPL SSEA (three hour minimum syllabus). Then the NPPL SSEA to a LAPL and the LAPL to a EASA SEP.