Hi,
I did ssb1 en ssb2 past weeks and finished them. Now I mostly ride outside, only when weather is bad I prefer indoor training. Since indoor training is only done now and then, it is difficult to follow a scheme. I ride in a group, have no goals at the moment. My only goal at this time is to be able to improve my fitness and be able to follow or beat everyone uphill:-). What indoor sessions do you think I should do when I am unable to ride outdoors? Thanks
It may help to think about what terrain you have access to, and what length efforts you can do uninterrupted before hitting traffic lights, etc.
I have some 2 minute hills nearby which are great for VO2Max workouts. On weekends, I head to some 20 minute hills for longer SS efforts.
edit: sorry, misread the question. I got mixed up and though you were asking which sessions to do outdoors. 
Use the new Train Now function that recommends workouts.
It would partially depend on what your outdoor rides look like. If they are mostly endurance up through sweet spot rides then maybe try to do a VO2 workout once a week. If they are super smashfests then maybe just recovery or endurance on the trainer to recover.
If you are mostly outside and not doing any structure then i would just try to fill the holes in your physiology that you think are either a weakness or are being missed in your outdoor rides.
Could try to do an increasingly difficult VO2 workout every day Tuesday after a rest, this will let you monitor your progress and let you know when you’re fatigued and need a break, if you start failing them.
If you don’t train indoors regularly, you can’t create a structured plan with progressive overload.
If indoors only happens now and then, just do whatever you fancy, or as said above, use TrainNow.
If indoors happens fairly regularly, for example one day a week, but it could be different days, you could follow one of the progressions from the build plans (ie vo2max, over-unders, straight sweetspot work), and just do it one day a week, even if its not always the same day.
Alternatively, you could make 1-3 days per week ‘training days’, where you’ll do a workout. If it’s nice outside, do it outside, if not, do it inside.
I would sign up for a low volume plan and get all the intensity sessions in indoors. Then outside riding can be all fun without sacrificing any progress.