Thanks ladies... You have all been very helpful!!

MantaRay... I was worried about high salt in cheese and that's what initially had me a bit worried. My son has been eating yoghurt since he was 6 months old and has had no reactions at all. It's his absolute favourite. If he is off his food at any given time, I just give him a yoghurt as I know he will eat it all!!

I think I will start him on chedder cheese then and give the 'plastic' kids stuff I bought a miss until I know for sure that he is ok with it.

Thanks again for all your responses.