Hi, I'm a student midwife and I have 4 children. I'm actually on maternity leave from my course and I'll be starting the second year with a 7 year old, 4 year old and 11 month old twins! 
Firstly, depending on where you are the course can be very very competitive. Over 2000 people applied to my course with only 52 spaces available. I'm in London though and I think elsewhere in the country it's not so bad. I had to do rigorous interviews whereas I know people who applied in other parts of the country didn't have to interview at all.
If you don't have 3 A levels you will probably need to do an access course. This is what I did. It cost several hundred pounds and was 2 days a week for 1 year. I also did volunteer work at the maternity unit in my local hospital. This is really important as midwifery has a high drop out rate and they want to see that you understand the demands of the job and you are committed to it. Also you want to see for yourself if you like it. Midwifery is not for everyone, it can be really tough, physically and emotionally.
Being a student midwife with young children is a challenge, I won't lie. There is no accommodation for parents, we do the same shifts everyone else does and this can be nights, weekends and we often get our rota at short notice making it very hard to plan for childcare. You have to work a certain number of hours in the year to pass the course, so if you miss shifts you get into difficulty quickly.You will need a good support network, either family, partner with a flexible job or very flexible childcare. I know 1 student midwife who is a single mum with no support, she's found a childminder who will do nights and weekends etc but it would be very very hard.
I suggest speaking to the uni, go to an open day, and see what volunteering roles are available at your local hospital. Another way to gain experience would be to get a job as a health care assistant.
It is a slog but it is the best job in the world, I would never want to do anything else and I can work anywhere in the country and be pretty much guaranteed a job when I qualify. You have to love it with all your heart, otherwise it wouldn't be worth it! Feel free to ask me any questions and good luck!!