How to be productive when I'm time-poor?

Heyy, so I (23f) work around 40-45 hours a week at a desk job. I don't drive so I get the bus, my daily commute is one hour one way, when I finish, I wait about 30 minutes for the bus and its an hour back home - So my daily commute is around 2.5-ish hours. I leave my house at 8am and am usually not home until atleast 7pm as my shifts can be 9-5:30pm (I'd be home around 7pm with the 30 minute wait as the bus comes on the hour and the hour commute) or 9-7pm.

I try to read a book or listen to an audiobook/podcast when I'm on the bus to be slightly productive

Honestly im exhausted lol I don't do much when I get home apart from eat a quick meal, watch TV for an hour or two and go to bed.

On my days off, I want to be active, I need to be active and productive because i'm so sedentary but I find myself stuck in my flat alot catching up on housework and chores that I don't have the energy to do after work .

Im also constantly tired, I wake up tired even if I've slept alot that night, my diet is kinda crappy aswell bc I eat alot of pre-made crappy foods like microwave meals :// I need to start mealprepping and I know that will help with my time management a fair bit

I started going to the gym but the way the buses were, (the bus at 7pm is the last bus home so I can't miss it) I could only go like once a week, after work if i finished at 5pm-ish, if that and I couldn't justify the cost

I'm kinda struggling to have a life outside of work, leaving this job isn't an option as its good pay and I'm only a few months in lol I'm trying to get more savings behind me before I start driving lessons as its £45+ per hour where I live and there's also a massive lack of instructors so everyone I've asked isn't taking on new students anyways

Any advice to be more productive would be helpful?