Help - Term time Contract and Sickness

[Confusedgirl]

Hi, completely new to this forum but I am desperate for help.
I work for a school (Academy) on a term-time + 1 week contract, only working 4 days a week.
Last year I was absent from work due to stress and depression.
for the first time the Academy have now included school holidays as sick, which I understand.
however, I am owed some days holiday when I was sick last year. The Academy want me to take these days during the school holidays this year.
Question 1 - as I am only paid for term-time plus 1 week and 31.5 days (24 + 7.5 bank holidays) annual paid leave this would mean that any other holiday is unpaid, although my wages are split over 12 months. Therefore surely I cannot take "owed" leave during those times?
question 2 - for the periods of sickness that I did not get paid (was sick for more holiday time than my annual allowance) then should I not of been paid SSP for this time?
My employer has said that SSP did not start until I had been off sick for some time, when my salary was reduced by half. They also state that I was not entitled to SSP for the first 4 qualifying days, although I had been of sick for some time at this point.
I know it's complicated, I am really hoping someone can shed a little light on the matter. unfortunately the union I belong to has had staffing problems so being passes around. I just need to know who is in the right.