Hi Claire Louise,
Im heading to Norfolk Island in May, and have had the same dilemma with travel insurance. I'm diagnosed with mets to bones, and am also trying to experience lots of travel, and ticking off that bucket list. I am covered for loss of luggage, changes in flight plans , however not for any medical or surgical hospitalisations related to any pre-existing medical conditions.
Its something that should be highlighted to government, so that people should not e discriminated for their disability.
Best of luck with your investigations, and don't let it hold you back from your travel.
Cuddles, Trace