Iam doing Msc in Public Health & Nutrition. I would like to do Phd in Psychology.But I donot have a degree in psychology. How is it possible to do That course

It may be possible if you have other knowledge to bring to the project. A psychology project related to public health and nutrition would probably be your best bet. You'll need to be able to show in your application that you have the determination, interest and self discipline to teach yourself the basics of psychology.

I have a masters in sociology and would love to find a phd in sociology with funding in canada or the united kingdom