Rather depends what the problem is with the Camellia - different fungicides treat different fungal conditions.

Leafs with brown spots on, Flowers with blight on etc

Leaf spot can be fungal or bacterial - if its fungal, there's usually pinprick sized raised bumps in the middle of the black spots. If bacterial, no raised bumps, and fungicide won't help. Flowers with blight? What does that mean exactly?

http://www.growsonyou.com/question/show/21054

I want to spray my plant with something to stop this happening again on new leaves. Somtimes i see white eggs on the underside

Did you check for scale insect on the stems?

no because i dont know what im looking for.

Oh sorry - scale insects look like little sort of shields, fastened quite tightly to the woody stems and sometimes to the backs of leaves. They're very small, probably about one eighth of an inch, and can't be dislodged easily other than by scraping with a fingernail or sharp implement.

Cant see anything on the stems , however after reading more on the net i came accross Cottony Camellia Scale then goes on to say they leave white fluff behind them, which i have seen on some leaves.

Do you think soapy water is ok to use with camellias

Won't do it harm, though how effective it will be I don't know. Worth a try if that's the recommended treatment.