@devvesa Highnorth also have articles about planning training and a book on training [including planning]. I think that the book is a good read.
I do my own planning. You must be prepared to invest the time into learning how to plan and how to adapt a plan for your goals and then for your day-to-day and week-to-week progress and feelings. I started planning by following a method outlined by Tim Cusick. He has a seminar available on Youtube in which he discusses the phases of training and the kinds of workouts that should go into each phase. One nice thing about Cusick’s method is that it progression from one phase to another depends on your ability to hit targets rather than depending simply on time. Whatever plan you decide to embark on, be prepared for the fact that this will take significant time – learning appropriate planning principles, reading around planning, working out your goals, identifying areas that you need to improve in order to reach your goals, making the plan, assessing your progress, evaluating the plan in the light of your progress, and adapting the plan.
Finding the appropriate workouts is not difficult. A simple library like Highnorth’s would work. TrainingPeaks also has a lot of free workouts that you can copy.
One thing that you will notice is that TP does not control your trainer if you are indoors; nor record your ride, indoors or out. So you will need a device to record the ride, which could be your headunit. In addition, if you want to do some rides in erg mode [eg: I often do endurance rides in erg mode, so that I can pedal away and think about something else / watch a video, etc], then you will need a device that can control the trainer. This could be an app on your phone.
Finally, intervals.icu takes the records of your workout / ride and analyses them in the usual way. I don’t bother to download my workouts to intervals.icu, but simply keep my calendar on TrainingPeaks. So intervals.icu does not act as my calendar, which is a pity.
I hope that this helps.