Just to clarify a few comments above...
You won't be able to use an NPPL to fly EASA aircraft (ie ones that have a certificate of airworthiness, not a permit to fly) after 8th April 2014, so you might as well just get the full PPL.
A NPPL is valid for use on EASA aircraft until 08th April 2015.
How to progress from a LAPL to an EASA SEP, I am less sure about.
See EASA Part-FCL FCL.210.A (b) - also in CAP 804 Section 4 Part C Subpart 1.
Until 2015, you can trade your NPPL (SSEA) for a EASA LAPL (Light Aircraft Pilot's Licence).
The conversion process detailed in CAP 804 does not contain an expiry date. I would expect this conversion to be available after April 2015.
I do often advise people set on a CPL as their end goal to simply start on a EASA SEP, so not to start training with us.
Hopefully any microlight school will also make you aware that flight time accrued in microlights (presently) does not count towards those hours required towards the issue of a EASA commercial pilots licence.
ifitaint...