Now just that remote J3 experience may not be bring any rights, but can some training (plus Skills Test?) gain me a J3 non-EASA "type" rating and a UK ANO CPL?
A J3 is covered by an SEP Class rating. So long as you have a valid SEP Class rating it can go onto either licence. Of course you don't need a UK licence to fly the J3 as it would also be covered by the SEP on an EASA licence which is rendered valid on UK registered (AnnexI) aircraft.