First Tyre Change

Hi everyone. My 23 plate model Y had its first MOT this week and was advised that the rears are now down to 3mm. Having never purchased tyres for this car im wondering what the best options are? The fronts apparently still have a bit of life in them at the moment so only looking for the rears. The tyre size is 255-45-19 W and currently has Hankook (summer) stock tyres on it. They've been great as ive got 30k miles (3 years) out of them. Ive seen people here talk about ion evos but I can't seem to find them in my size. Any help or advice would be appreciated! I'm based in Scotland.Thanks in advance!