You need to inform them. Some exclude and some are okay. What I meant was if there are some real issues then online arranging wont be easy.

www.jdtravelinsurance.co.uk they say if the doctor is happy that a patient is well enough to travel and plans are realistic, then cover should be reasonable.

http://www.avantitravelinsurance.co.uk/

http://www.freedominsure.co.uk/

Freedom can do things like blood pressure and diabetes online.

But also if a member of the trip as issues then both parties need to make their insurance company aware, as you get affected.