Yes, ofcourse you can start cycling at home. It the best exercises. But doing cycling alone doesn't not help you to reduce weight. You have to follow regular exercise and diet.
Next Steps
you can consult me though this forum to check your diastasis Recti and after assessing your diastasis Recti I will be recommending you the level 1 exercise and gradually increasing the exercise intensity and type.
Health Tips
Before Starting your exercise do check for your diastasis Recti and then according to it you can do exercise.
Doing exercises without checking your diastasis Recti will not reduce your mummy tummy (flabby belly)