Tips for outdoor training

Can’t do outdoor training for 100km and only on trainer. Can anyone give tips and training ?

How long have you been riding? How far can you ride now? With a 100km ride only two months away, I’d hope you can at least to 40-50 km with no problems, else you’re going to have a very difficult time working up to 100 km in that short of a time. The more details you can provide for your experience on a bicycle and your current fitness level, the better help you’ll get. And I hope you have a good TV plan of some type - you’re going to need it given all the time you’re going to be riding on that trainer.

Why Can't you? Is it due to circumstance? If so Indoor training is a fine alternative till you can.