You should be fine to cycle once your wrist is out of plaster (but do check with the doctor for specific advice)
Don't be surprised if you find your wrist aches considerably for a month or two and with this in mind, it is worth considering altering height and angle of your handlebars to reduce weight on your wrist when cycling. It may also be helpful to adjust the brake position to reduce wrist flexion. While on the subject of brakes, check that you can achieve a full emergency stop.
To be honest, I am more surprised that you are planning to cycle so soon after your hysterectomy - so I hope you discussed this with your surgeon?