I had a 2006 Focus TDCI and a 2002 Focus 1.6 petrol special edition. Great car, cheap to run and repair, the 1.6 Focus was actually better in my view than the later model which lacked character in any way. My understanding of older 3-series is they're quite expensive to keep going. I only know this from a friend who has had one for the last couple of years (2003 320i Coupe) and things like the electrics have played up and he's had to have some engine work done too - it's broken down three times in the period. By comparison my 02 Focus I ran for three years and it never missed a beat, most expensive was an ABS sensor replacement.

I would've thought that at £2k you'd be better off with a last of the line Focus from 2004/05 with a low-ish mileage and all the extras they put in run-out models?

I agree ford are cheap and reliable but not exciting in any way. BMW in your price bracket are likely to be shot to death. Currently on a Jag but the last car was BMW318d and I did 150k with only servicing and no issues. Rush on wings can be an issue on pre 2005 car due to the intro of water based paints and many manfactures being quite slow to find solutions to the issues. I personally would not go with a pre 2005 BMW 3 series as quite a number of important issues got fix with the face lift version i.e. turbo problems.