Perhaps consider the mk1 Mazda2, which in many respects is similar to the Ford Fusion - decent boot size/flat loading lip and easy entry/high seated position but with some/most (?) of the Ford mechanicals replaced with Mazda bits.

Generally very reliable by all accounts, although HJ's Car-by-Car review says that auto versions have experienced problems with an 'ASM module' after about 4-5 years which costs £1500 to replace, so you'd need to check that it has been replaced.

The mk1 Toyota Yaris or (if you can find one) Yaris Verso (if you are not bothered about the odd looks) are also recommended (the Verso looks to have the same practical qualities as the mk1 Mazda2). I wouldn't have thought parts for these and the Mazda would be too expensive compared to the Daihatsu/Kia/Hyundai models.

To be honest, you're going to be taking a risk with any second-hand car that costs £1500 or less as its likely to be around 10 years old (at least for the Japenese marques), which is beyond the anticipated 'useful life' of most modern cars, and as such, have to expect some major repairs over a 3 year period. If cars were so reliable that nothing went wrong for 15+ years, we'd never change them and all the manufacturers would go out of business due to a lack of new car sales!