Is a parking ticket valid if it says "No waiting at anytime" for reason. The road was double yellow lined, but I was parked fully on the path and not actually on the road itself.

As far as I'm aware its "illegal" (or implied at least) to even park half on half off a kurb, let alone on the whole thing (iirc)! The ticket is probably referencing that, as your not allowed to stop there full stop!

Oh I know I'm not allowed to park on the path, but they'd have had to put a ticket on my car for that, so wondering if they've got the right code (L131) for my ticket to make it valid or not.

ooohhhh........! I take that back then, sorry- didnt understand that quite right! I'm not sure where would have the information for the parking codes, the DVLA maybe?? :S just a guess...