My advice would be to complete your nursing degree unless it is really making you miserable. You could then apply for accelerated (four year) medical courses as a graduate. If you aren't successful, you can continue working as a nurse (gaining experience, contacts, and applying every year if you want...) as well as seeking opportunities in advanced roles, e.g. as a Nurse Practitioner. During that time you would be gaining experience and your child(ren) will be growing up. You could apply to medical school every year if you wanted - lots of students on graduate entry courses are in their 30s and 40s (and 50s...!).
One consideration is whether you are free to move across the country. All medical courses are very competitive and you would be very restricted if only able to apply to one or two. Leicester Medical School has a course that specifically recruits graduates from other healthcare degrees (nurses, physios, etc).
Another possibility is to look at the emerging Physician Associate role. Graduates applying to the Manchester programme do not pay fees and receive a (reasonable) salary during their two year training: www.mhs.manchester.ac.uk/study/postgraduate-certificate-diploma/courses/physician-associate-studies-pgdip/?pg=1#course
As brokenmouse said, medical training is possible as a single parent but would be very difficult. Having said that, it's presumably not easy as a nursing student either with placements in different hospitals and anti-social shifts?
In any event you need to do your research very carefully. Getting into medical school isn't just a matter of having the right grades - a lot of people spend a year (or many years) getting together everything they need, e.g. varied work experience, carefully selecting the right medical school, sitting admissions tests, etc. You will obviously be ahead in terms of having some clinical exposure but it would still be worth shadowing a GP to see whether the grass really is greener on the other side.
Some good resources are www.thestudentroom.co.uk/forumdisplay.php?f=195 and the book "So You Want To Be A Doctor?" by Dev, Metcalfe, and Sanders. Course websites should also state their selection requirements very carefully.
DOI: SpR in a surgical specialty and still enjoying my job for the most part...