phil
What are your options? You don't have the money to pay your mortgage, so take advantage of the 3 month moratorium to which you are entitled without giving any reason.
You can see what happens as the three months are coming to an end. Maybe you go back to work earlier? Maybe a relative lends you the money until you get back to work?
Your contract allows you to take two 3 months moratoriums but not at the same time. Towards the end of the 3 months, you might ask for another. If they give you one, it probably won't affect your record.
But you don't really have any choice. Recovering your health is your priority now. Be careful about your credit rating, but if it suffers, so what? It just stops you moving. If you recover your cheap tracker, you may be reluctant to move anyway.