The CAA will not issue any EASA licences until the changeover date which I believe is in November so if you send it now it will be a JAA PPL assuming that you took the training according to the JAA syllabus.
The Benefit is that as of 8th April all JAA licences became EASA licences. So your shiny new PPL will have JAA stamped on it but be acceptable under EASA. That means that you will not have to do anything until you licence is up for renewal and then you will be issued with an EASA licence.
Hope that helps