Golf 1.6tdi Bluemotion.
2012, 1 owner from new, full history.
259k miles but at that age you can guarantee it’s covered most of them on a motorway, your basically doing more of the same to it.
Despite the miles I’d still expect it’ll be reliable (especially compared to some of the suggestions here) and it’ll be a world away from what you have now.
A curveball suggestion, sure, but it’s the sort of thing I’d consider personally for your requirements. Under budget too!
http://www.autotrader.co.uk/classified/advert/201711171342294