I'm sorry you're in this situation, but this will be the beginning of a new chapter. You will have a brilliant life with your daughter and from my experience a very close relationship. Some practical things.
Work
Let work know your change in circumstances. Is there any opportunity that you could negotiate WFH, even 1 day a week, to make your life a bit easier.
Ensure you update your pension etc so that your ex partner doesn't inherit any payments. Update your next of kin etc.
Money
Use the online calculator on gov.uk to work out child maintenance. You will have a rough figure if you know his salary. This is the minimum figure you should receive.
Get a benefits check just in case you are entitled to any. Make sure the child benefit is going directly to your own account. You can change this easily online if it isn't.
Set up a savings account for your daughter. Use this to save any birthday money gifts (if you can). Try to regularly save into this for when she's older, even £20 a month will build up. Also ask grandparents for monetary gifts rather than lots of unnecessary items. Or for items that you need like clothing etc.
Day to day co-parenting
Try to keep it as amicable as possible. Do not be derogatory about your ex partner (in front of your child). You want them to have as healthy a relationship as possible. Vent on here or to your friends.
Use a parent plan template to keep you focussed on how you will co-parent. Try to arrange access etc between you rather than going down a legal route. www.cafcass.gov.uk/parent-carer-or-family-member/my-family-involved-private-law-proceedings/resources-help-you-make-arrangements-are-your-childs-best-interests/how-parenting-plan-can-help
Once living arrangements have been set up you can set up an online shared calendar to keep on top of where your daughter will be.
Do not try to do everything yourself. Ask for help (and use it) from friends and family. Could you set a routine so your daughter stays a night with their grandparent once a month? This would be really helpful for you and for her. Use that time to do something for yourself.
Personal
This is such a difficult time for you emotionally. Life hasn't turned out as you expected. It is really lonely. I kept notes on my phone about all the things that pissed me off about my ex partner and every time I had doubts I reread it. Note down everything you feel, everything he does. He sounds like he's in manipulation mode, so that list could be really helpful!
The Co-parenting Handbook by Karen someone is a helpful read. You can get them secondhand online.