Another update - after having my panic attacks come back after a holiday (when getting ready to go to work) I made another appointment with my GP, and he recommended I put my health first. He offered a sick note, however of course I wouldn't be able to keep the Shop open with this so I declined.
Looks like I'm leaving.
Horrible things, you never know if you dont try. you will most likely be happier working for your self and being your own boss.