The LAPL medical standards are virtually the same as the NPPL (we lobbied for that!) but there may be a few minor differences - I haven't compared them for about a year when they were at the proposal stage. What I do know is that those with insulin-dependent diabetes will not be grounded as was for a while the possibility. The details on this are still being finalised I think in the AMC material with strong (favourable) input from UK CAA.
The GP system will change for the LAPL because the GP will need to sign a certificate rather than endorse your self-declaration. But providing you do not have any disqualifying conditions it should be very much like the NPPL. In terms of acceptance by GPs, I understand the UK CAA medical department will be informing the GPs on the new system in due course, presumably through the BMA. So hopefully your GP will know what is needed by the time you need to transition to the LAPL from the NPPL.
If you go to the link below:
EASA - Opinions
and scroll down to Opinion 07/2010 you will see the rules that were submitted to the EASA Committee (this is a member states forum) earlier this year; I do not recall any changes in the committee, but the Opinion does not have the very detailed AMC material which is still being worked on.
Part FCL and Part Med are due to be published in the EU Official Journal next month, which means they then become law from next April. However there is a three year transition to obtain a licence (to April 2015) with the appropriate medical.