We use Tyser for our annual travel insurance, it covers my wife's pre-existing medical conditions and is as reasonable as most annual family travel insurances just under £100. Mrs MTP has epilepsy (well controlled), but previously this has always been precluded from our health insurance but we found out about Tyser from one of the various UK epilepsy support organisations' websites. If it is a pre-existing medical condition then it may be worthwhile if there is a support organisation for the condition checking with them for specific advice.