I don't know if I should do intervals, speedwork, etc or just stick to basic riding keeping my HR in zone 2 or 3.
There's no way for anyone but you to know these answer.
Think in terms of exercise theory. A couple of my favorite "advisories."
Remember the hard/easy rule - in other words, usually -every other workout is hard or easy.
Remember the necessity of sub-maximal - to maximal ratio. That means, only a fraction of your total time spent can be "all out" efforts - usually less than 30%.
Understand the specificity of your workouts to your goals. Your approach to working out should keep in view how it reflects the conditioning needed to be fit for your goal scenarios.