A Uk or any travel insurance company will check travel history prior to the claim, they will want to know the travel date backed up by original hard copies and one sniff of fraud and they will come down heavy, by fraud I mean claiming to live in the UK to get cheap international health insurance, and yes immigration, maybe I should have posted UK passport control, everytime passport control puts your passport under the scanner it is not for fun, you are booked back in the country and it this info many agencies have access to, unfortunately I speak from an expensive error of judgement !!!