Philippa, I don't know what the exclusions are in England regarding military service, but in the US if you have confirmed myotonia congenita you would not be allowed to enlist.
Hi Garrett....I read your post, and wanted to share with you that I served 12 years in the US Navy, achieving the rank of YN1(SW)(surface warfare specialist), and also served in Operation Desert Storm.....I joined the Navy when I was 20, and had the same types of difficulties with the physical rigors of the military.....my problem was....I didn't know I had MC....had it been diagnosed, I'm sure I would have been discharged. I didn't find out I had MC until I was 50 years old, and was able to see a neurologist at the VA, who diagnosed me....it was quite a relief, knowing that there was something with a name to go along with my symptoms, and that I wasn't just "clumsy"....anyway, wanted to share that, and thank you for signing up to serve our country....and as a Firefighter, you are doing just that!....from a proud Veteran, Thank You!