Why spend £7k? The VW 2.0 TDi powering most of the ‘fun’ cars suggested above isn’t exactly the most reliable unit and there are lots of reports of major issues with injectors and fuel pumps…. to be honest any modern turbo diesel has the potential to chuck a £1k+ bill at you so I’d want to build this into my budget.
DaveyBoyWonder has the right idea, I’d go for something like this BMW 330d Touring (204bhp, upto 230 easily with a mild remap and lots of smiles), Spend £500 on an auto box flush and general once over and keep £1000 back as a buffer for on-going maintenance and any issues.
http://www.pistonheads.com/classifieds/used-cars/bmw/e46-3-series-98-06/bmw-3-series-330d-sport-5dr-auto-diesel-touring-3-0/1570645#
I’d be pretty confident that it will outperform a Golf / Focus diesel .etc in every area apart from maybe dropping a few MPG – and if bought at the right age, are likely to have been looked after a lot better than the run of the mill stuff. Don’t be put off by the higher mileage, it doesn’t mean anything beyond a few years old & my E46 330ci still felt nice and tight at 120k
A Volvo D5 would also be a good shout, but won’t drive like the BMW does.