Thank you for reaching out to us.
We follow the view that a total hysterectomy does not make a woman niddah and that there is no need to immerse afterwards if a woman was not in niddah prior to the procedure.
If we understand you correctly, you had a total hysterectomy, removing all of the cervix along with the uterus. In that case, there is no requirement to immerse now. Some women choose to immerse voluntarily, without a bracha, to take leave of the mikveh.
Learn more about halacha and hysterectomy here.
Refuah shleimah! Please let us know if we can be of further assistance.