Could you defere for a year? in that time you could either do an access course or work, either way your mind will be made up.
Most access course require you to be 19 or older to join although I think there is something called first focus or foundation for 19 below students.
Have you though about doing a science foundation year at the university you would like to go and do your degree at instead? T
I am just coming to the end of my access course (science pathway) and I can tell you it isn't easy or cheap! Basically learning at A level standard but condensed into a year. If you are struggling to motivate yourself now I think you may struggle on an access course. However, with you being a school leaver you want have to take GCSE equiv maths, english and science, so you're work load would be slightly less. I am currently studying 6 classes, some of which are nearly either a double or triple subject.
Apparently the access course is changing come Sept 2013 and the fees are increasing too. (You may get the course for free depending on your age though)
If it is something you really want to do then do it, however, do lots of research as some universities do not accept access course to get onto their degrees. Midwifery is very competitive too, some course have 600 applicants for 30 spaces.