It's free for all 3 and 4 year olds at the moment. 15 hours each week 38 weeks of the year. However. The 30
Hours scheme is:
a) only a trial from this September in a few (7 I think) areas;
b) likely not to be implemented everywhere because not every setting can afford or is able to offer 30 hours;
c) may not come into existence at all depending on the results of the trials
Basically, don't build your life around it, get a job whew you can afford the child care you need for that job, because there will be no guarantee that it will exist to meet your needs.
I don't know how the 20/10 hours would work; again, depending on what area you are in, you may get 30 hora regardless, or only if you meet certain criteria, or not at all. You may not find a setting that offers the 30 hours you need. Sorry to be so negative but it really isn't a good scheme - it's ill thought out, not supported and rushed through parliament.