Aerosols and similar are obviously ok like the stuff you buy from halfords ect and im obviously not talking about that. If your talking about proper paint then of course its illegal! Its basiclly poison mate and by law needs to be painted in a spraybooth and go through the extraction filters ect to be safe and the painter needs to be wearing a suitable respirator, why do you think there is so many warnings on paint tins ect. You can buy paint from lots of places because there is almost no policeing of it and paint factors are businesses who are there to make money and most dont give a shit who they sell to.
Im not saying anybody is going to get fined im just pointing out thats illegal and you are liable