Your old brown UK PPL is still valid, you just need to renew the SEP rating on it.
Your UK JAA licence is no longer valid because they were all issued for a limited period. You will find the expiry date within you licence, However updating it to a current UK PPL, which will be in accordance with ICAO, as was your previous licence, is not problematic and will be issued for life. If you hold a RT licence then that requires nothing further and the privileges of that will be embedded into the new UK licence.
There is no such thing as a EASA licence. Each member state issues its own licence but in accordance with EASA regulations. For English speakers Ireland is favourite to to obtain an EASA approved licence. It is not a conversion; you do not give up your UK licence to obtain another countries licence including those of the EU. You will be given credits based on your UK licence