I know that the NHS is different from the US healthcare system, but do keep calling. Be an irritant that they will take care of so they don't have to hear from you again in a few hours. When you call, tell them everything you have typed in your post about your diagnosis, so they understand why you are calling. Tell them it's urgent. If necessary, go to the hospital emergency/casualty. Your therapies need to begin as soon as possible.

Is there some kind of patient advocacy group that could help you?