Hi Co Co,
Don't worry!
Send your MR letter in now or as soon as you can. You will need to show a good reason for being late. I'm sure that if you are only a few days late and carefully explain about your health and support worker there should he no problem. If you can show such good cause, you have an absolute time limit of up to 13 months from the date of the relevant decision.
I hope this helps.
LL26
Nothing on this board constitutes legal advice - always consult a professional about specific problems