I am wondering what kind of estrogen I would have to take (oral, gel, etc) if I were to remove my ovaries and  I was looking for some information about using them. Would I be given exactly (same dosage) what MTFs take? Is it basically because they're not natural and are from an outside source/synthetic that they will have side effects like any other medication (especially taking it long term)?  So I was looking for what the side effects are.
Thank you in advance.

It would probably be a lower maintenance dose like what a postop MTF would take. Preop MTFs take higher doses for faster feminization and in some cases to suppress testosterone. You won't have that issue.

Side effects? Potentially liver if you take them orally. I don't think natural or not matters, it's the method of introduction into your blood stream. If you take it orally the liver has to metabolize it.