There's some fairly powerful and fun to drive 2.0 diesels available, if a diesel suited my car use, I certainly wouldn't discount them. My old Mondeo ST TDCi would have been £21k, 9 years ago, as standard it was fun to drive, bigger intercooler, decat, performance exhaust and remapped to 190Bhp, plus Eibach springs, it was even more fun, certainly didn't feel big to drive, Modern diesels are on par if not more powerful.
If someone gave me a £20k diesel, I'd be straight down the Ford dealer with it and my Focus and swap them for an RS or a Mustang. Save me using my own money.