Thank you all, all your messages and help have been great and really helped stop me going crazy today.
I've discovered (as laluna also said) that DD should not be contagious by Sunday. I contacted my insurance company and told them this. I also explained that I have no way of getting a doctors note until Monday. The insurance company advised me to go along on Sunday and see what happens. If they will not let us board the plane, we need to get something in writing explaining their reasons, then phone the insurance company. If we do this, they will accept a doctors note written on Monday and we will get our money back

.
So, if you haven't heard from me by about lunchtime on Sunday, we'll have made it to DLP

. For those of you going to the meet on 7th, if I'm not there it's probably coz we never made it onto the flight
On the plus side of it all, it's helped me make the decision that I'm not going to upgrade from half board plus to half board premium