Night time VFR is not allowed in Spain, well this is what all my instructors have told me.
Although you get snippets referring to it like the quote from C172, and the rules of night VFR are studied in Law, I think this is to be JAA compliant and nothing else
If you submitted a flight plan for a night VFR flight I'm sure it would be rejected on activation.
If anyone has ever done it though I too would be interested.