Spend the money down the pub instead. Just ride your bike a lot, mostly steady. And occasionally hard for durations of 4-15mins, with rest around 2 min between efforts. Efforts dont need to be over 95% hr max but around 90-95% avg is good. With total duration around 40-60 min HARD work a week.
What's best for training plans? TrainingPeaks or TrainerRoad?