Yes PaulisHome, you're right I already checked with the CAA and there are all the forms needed to get the SPL through the CAA UK, the only thing is that there are not ATO as such until April 2018. As you said, according to EASA you only can hold licences from a single Member state, that's the reason why I need to get the UK EASA SPL.
Thanks to all for your help, I will definitely do the paperwork this summer when the weather improves.
Regards
P.