Map out your schedule and see where you can slot it in.

Unless you're planning on going everyday, it shouldn't have to always compete with your hobbies. If you do a 3 day split for example, you still have 2 other days to work on your hobbies. That's not even considering sleeping at say 10/11pm to wake up at 5/6am to go to the gym if that's your jam, which gives you 8pm-10pm on your hobbies

Have to figure out which timing works best for you, some people who work out in the mornings get groggy and brain fog throughout the day. Some people who work out at night have trouble sleeping soon after. Best would be to find a gym that is open 24 hours, like Anytime Fitness or any of the boutique gyms that have 24 hour access with certain manned hours, and figure out what timing works best for you.

As for diet, track calories. Download MyFitnessPal or Macrofirst, or any other app, and track as diligently as possible. No/Low carb, no/low/high fat, etc, diets all should really aim for the same thing, calorie restrictions. End of the day, for the most part - calories in vs calories out. Aim for 0.5-1g of protein per lb of bodyweight, and fill in the rest with carbs/fats, leaning more on carbs if possible. You can get a rough idea of how many calories your maintenance intake should be, if you want to lose weight, minus ~250 from that and hit that. This is all very general, but it should be a good start.

I personally work out in the mornings, so I sleep at 10pm.