It sounds as if your lady wants a car use to go to, from and for work purposes.
As much as the Williams is unquestionably a better hot hatch than the Ibiza Cupra, it might not be the best bet for this sort of use. Dont get me wrong - my Willy is - no joke - more reliable than my parents new Volvos. Its never let me down, is mint and is a buzzing drive.
Mechanically and cosmetically, a 100% Williams comes at the behest of a generous wallet and Id say youd be looking at a few £200-500 bills every year to keep it tip top. The Willy may be relatively cheap to buy and may hardly depreciate, but it will hit your cashflow from time to time if youre on an average wage.
Youll also find that, like any older car, little niggles like bulbs and switches expire and can take a little effort to find. Thats fine if youre used to it or actually enjoy getting handy, but its not usually what people want. I also reckon that the Willy is an impractical car in terms of worrying where to park it and keeping it mint in day-to-day use.
Mind you, Im not convinced that a SEAT Cupra will be considerably better by any of these measures. The only way to access trouble-free motoring is to buy an excellent condition car with a warranty!
If you want to have a look at a Williams, mine will be at the meet in Cardiff on Sunday.