Whilst EASA becomes Law in April 2012, the CAA will not issue EASA licences until 1 July 2012. Existing RFs who currently conduct PPL training will have until April 2015 to comply fully with the EASA requirements which include becoming approved as an ATO. Part of their approval requirements will be to detail how and when examinations can be taken.
Once approved as an ATO, schools will have to comply fully, but the transition to ATO will be gradual, and if previous experience is anything to go by, will be left until 7th April 2015.
You are not likely to be affected in the short term however; the PPL exams were scheduled to change in September 2011, this has been delayed and may be to facilitate alignment with EASA requirements, which stipulate administrative arrangements for exams that cannot be fulfilled using the current UK system.