I'm in a similar situation.
Lone mum to 2-year old twins. I work in a senior, stressful role. Luckily I work from home, so no commute. Work about 50 hours a week.
I've two nannies to cover the day! The main nanny comes at 8:15am and leaves at 5:15pm. The second nanny comes at 5:15, and leaves at 6:30, 7 or 8pm, depending on the day (I've meetings till those times each day).
I do all cooking for the twins, and make everything from scratch. Every day at 12, the nanny has a break, while I give my kids their lunch. (They have their main meal at lunchtime).
I give them dinner about twice a week.
I do all bedtimes alone, and then back for more meetings (with the US) till about 9/ 9:30. Then I have dinner, and go to bed with a glass of wine and my book!
I don't have a cleaner, so have to put up with the house not being as clean/tidy as I'd like. The twins don't get bathed as often as I'd like.
I've no time for me, since I'm either working or looking after the toddlers. I love my hour in bed reading/mumsnetting though.