Program feedback for beginner

I'm 40M, and just this week started a gym membership as I want to tone, lose a little more fat, and build functional strength. I currently run an average of 30km per week, so cardio is already covered outside of the gym. I've adapted a program based on a video by 'trainer winny' on YouTube, but swapped out bars and bells for machines. At least for the next few months I'd like to stick to machines, as they are more readily available in my local gym, and I can switch exercises and weights much faster. I'll also be able to concentrate on gradually adding weight with less risk of injury. This is the workouts I started this week (all machines):

Workout A Chest Press 4x8 Seated Shoulder Press 4x8 Leg Press 4x8

Workout B Assisted Pull Up 3x10 Seated Row 3x10 Bicep Curl 3x10

I rest for approx 30s to 1m in between sets. I've very much enjoyed the two visits to the gym so far, but the workout seems really short; I'm usually done within 20 minutes. I've seen other beginner programs which I believe also use only a few compound exercises each workout, such as stronglifts 5x5 (my program seems to more or less match the 5x5 in terms of exercises, but using machines rather than free weights). I'd just like to know if my program is generally ok? Is 20 minutes per workout effective? Please let me know if there's another compound exercise I should be adding, or if I should be doing more reps or sets. Also, are there any important muscles I'm not working using the above program? I certainly don't want to be in the gym for 2 hours at a time, but I'd just like to check that what I'm doing is effective, or if there are some modifications I need to make.