returning to gym/exercise after a long layoff

I'm in a place where I can now get back to exercising regularly and I was wondering about a solid cardio program to complement a lifting program (strong lifts 5x5 or Starting Strength - both of which I used and am pretty happy to begin again) - I used to do crossfit but don't have the money for that - so finding good programs that have progression I can follow for 3-6 months from beginner onwards

Is there a good source of info/programming for cardio along the same lines as 'starting strength' for example?

IMO the best cardio program is running or riding the North Shore trails. I have done the spin class/crossfit thing in winter, way better to be outside and go hammer, plus it's free.

Do a ride up NQ a 2/3 times a week and that will get your cardio sorted pretty quick. If running,  alternate the types of run training. Do an interval session up steep hills, then next run do a easier tempo run, and so on. Keep upping your distances every week. If you don't want to run on the trails, you can find lots of hilly street circuits all over the place. Princess park is a good loop for climbing intervals, nice smooth gravel circuit, easier on the legs,  just need a headlamp after work this time of year.

Trained a guy at work who had been out of the game for a number of years. Would meet at the cemetery lot above Cap college, do a warm up run along the diamond trail to the canyon, then do intervals up and down the stairs that lead to the canyon bottom on the Baden. Great place to train.

That sounds perfect, I'd rather be outside training in areas I know than inside on a spin bike.

I feel like NQ would probably put me above a reasonable heart rate this early in, so maybe intervals up Old Buck/Mtn HIghway and aim for NQ as the week test. I'm not sure where the diamond trail is but Lynn Canyon and headwaters have an abundance of stairs, so I think I'm good for those as well.

The climbing trails on Fromme are great for running /power hiking. Have sections that are a bit grunty and then flatter recovery sections, there is old skid roads everywhere that criss cross the mountain, so you can do a different circuit every time. I really enjoy doing my running training there, easy to get away from other trail users if you want some space.  Going straight up the old lines like Starfish, Grannies, Jerry rig etc is great workout and it's cool to see the old stunts being reclaimed by the forest.