40 mile bike ride training using stationary bike

I'm doing a 40 mile bike ride in a few weeks and I want to push myself hard training. Unfortunately my outdoor options are kind of limited to get in long rides with hills etc so I was thinking about pushing myself on a stationary bike.

Does anyone have any programs or routines that they could push me towards that mix HIIT, hill riding, and endurance riding so that I can be ready? I think I'm gonna do a spin class once or twice a week, but I'm looking for a solid program to follow.