I have a B.sc in Microbiology and MB.ChB and I want to go for PhD. Please how do I go about it.

Go to nearest university and know it.........

I don't think I understand you question fully.  What do you mean by the fee required?

The minimum requirement for a PhD is a 2:1 at bachelors level, so if you have that you could theoretically get a PhD although getting funding may be more difficult now without a masters, but it is possible. If you have any relevant work experience that can go in your favour.