If you currently have travel insurance through your FlexAccount, please note that this cover is only valid for permanent residents of the UK. To qualify you must have a permanent address in the UK for at least 6 months a year.
If you're in the British Forces you'll need to demonstrate a permanent UK address when you make a claim, and be a permanent resident of the UK for at least 6 months in the last 12. Trips must start and end in the UK to be valid.
If you live outside the UK you will not be able to use the insurance benefits (including travel insurance) that come with FlexPlus accounts and will still have to pay the monthly account fee of £13, so FlexPlus may not be the right account for you.