Where are you going? I use Ehic plus if travelling in EU. Although theres a headline on the webpage for over 65’s it covers all ages. https://www.ehicplus.com/
Like @Boo1979 I've used EHIC Plus in the past and they were pretty good. This year I've shifted to HolidaySafe and got a better deal.https://www.holidaysafe.co.uk/ You may find better quotes elsewhere as mine are for an ancient relic with a couple of health issues!
You'll probably find the best deals from companies that don't advertise on price comparison sites.
Happy hols!!
I use Sainsburys Bank ( I dont bank with them). Never had an issue and have had to make a full claim day before we were due to go one year. I dont have any premium loading for my diabetes but my OH/eldest have a small loading added for ear issues.