Was I wrongfully dismissed?

I lost my position with GKN Aerospace in Filton, Bristol where I worked as a Skilled Fitter back in August 2015. I attended a 'Welfare meeting' as I was out sick again due to Fibromyalgia. At that meeting I was given a choice, take severance pay or face a final hearing over a quality issue. Management at that stage were putting me under increasing pressure to up my work out -put and were not interested in hearing how my illness affected me. This stress combined with my illness made it hard for me to fulfill what management expected of me. They didn't try to redeploy me or make sufficient (reasonable) adjustments that would have helped me, though they did allow me to work two days, have a day off then work another two days to fulfill the hours they wanted me to work. I'd been on a phased return to work for many months and was told I was expected to return to full hours within a couple of months otherwise my job was at risk. 

I feel that GKN could have done a lot more for me and since then, my health has deteriorated, perhaps in part as a result of being pressurised to leave. I had only a few days to consider my options and don't feel that the Union or GKN were supportive enough. 

Please can you advise if there is anything I can do as I feel so badly let down. Surely GKN have failed to truly take into account my disability and the affects it has on me. 

Many thanks in advance.