How to live as a single parent?

I earn 47k (Student loan - Plan 1)

Currently married but looking at divorce.

3 children, including an 11 month old.

Work 9-5 full time.

Commuting into London twice a week - Travel cost per month £600

Food - £500

Council Tax - £150

Car lease per month - £500 (I couldn't get anything, and this was arranged via my partner)

Childcare costs - £700 per month

Partner pays mortgage and utilities.

I'm struggling to see how I can save or manage finances as a single parent.

Am I missing something here 🤔