What are my rights as a new employee?

I was recently offered a part time job which I began on Monday morning 27th November. The contracted hours were to be Monday 9.30am - 1.00pm, and Saturday 9.30am - 5.00pm. I completed the Monday shift and when I arrived on Saturday I found out that they apparently were not expecting me, but they asked me stay until dinner time, which I did and was more than happy to do so.

My next shift was scheduled to be Monday morning 4th December but unfortunately I suffered multiple massive tonic clonic seizures the night before and was taken to hospital via ambulance. When I emerged from the 'fuzz' I immediately texted my new employer to advise that I was in hospital but hoped that I would be well enough to attend the following morning. However the doctors thought that as my seizures had been so severe, as witnessed by paramedics they kept me in for ongoing observations. Early on Monday morning whilst still undergoing said observations I again texted my employer to explain the situation and I apologised profusely that I would not in fact be able to attend. I received no response to either message. When I got home from hospital on Tuesday 5th December, having still heard nothing from them, I called them to apologise again, and they told me that they had decided it was not going to work out and they no longer wanted me to work for them. They insist that they are not being discriminatory but I beg to differ. I have been unable to find a precedent so I am looking for some guidance as to my rights in this matter. I would be incredibly grateful if anybody can advise or if anyone knows of a precedent? Incidentally they were well aware of my epilepsy, we had discussed it at length during my interview and it is also outlined in detail on my CV.

Hope you can help
Donna