I would say focus on the things you need to do in life to make becoming a parent seem like a positive choice. If you are in a relationship with someone who doesn't actually want to have another child, that's a pretty good reason not to have one. I should add, there is no such thing as another parent taken a child away from the non-custodial parent, except maybe cases of parental kidnap. If he wanted to raise his child and be involved in his/her life, he could be. If he doesn't want to be, that's a good reason not to put yourself in that same situation where he'll run off and not want to be in your child's life either. Work on building your relationship more, supporting him in getting involved in parenting his child if he is open to re-establishing those ties, or find a relationship with someone else where you want the same things. You can't make anyone want to have a child if they don't. If you don't have enough in common that you can see yourselves taking the same path in the longer term, maybe it's a reason why you aren't compatible?
But really focus on yourself. If you feel like you aren't ready and can't financially support a child in your current situation, change that so that you can be in a situation where you can. Go back to get additional qualifications or training. Set yourself up with a good job that you can see a future with. Think about where you'd need to get financially before you could comfortably support a child. Think about what you want to do with your life. There is more to life than just babies. Though my daughter is the best thing to happen in my life, she's also not the only thing. They are also only tiny for a short period of time, and then they're off to school and you need to have a full, meaningful way to fill your days and make a life for yourself. I love the work I do and it will provide us with a good, stable life. But that was only possible because I put in the hard work to making a stable life for us before she was born. Is it totally possible to get additional training or go back for a degree after you become a parent? Yes, totally possible, but much, much harder. If you do that hard work now, it will be much easier later. Childcare is expensive, so if you have plans for starting a course or want to get into a certain career, get your foot in the door before you're having to spend £700-1000 a month on nursery fees. It will also give you something for yourself to focus on to help make the wait easier and feel more purposeful.
Having a baby is also just really, really hard. The more secure everything in your life is, including your relationship and other things, like your living situation, finances, etc., the easier it will be. You don't need to be rich and babies actually don't need much stuff at all, but they make life a lot harder. I've done a lot of hard things in my life, but being a parent is by far the hardest. It's not all cute clothes and playing with a baby. It's wonderful and rewarding, but it's also exhausting and it means you literally have no time for yourself at all (getting a shower used to be the most glorious luxury ever), and you don't have time for friends or going out or doing a lot of the fun things you can do when you don't have a child, and you will fight more with your partner in the first couple years than you ever have before. It's hard. Make sure life is as easy and stress-free as possible, so that when the added stresses of having a baby comes, you're ready to handle it because you've sorted everything else out first.