I get asked this question a hell of a lot in my field (VOSA) and all I can tell you is that all fuels have to meet a certain given criteria, especially in this country.
If you take all diesels on the road including HGV's which believe it or not, have to meet Euro 3,4, 5 specs or above depending on age, they are even more (sensor) sensitive than modern cars yet how many do you see have issues with sub standard fuel? They have to meet far more stringent emmisions tests than cars.
Alfa's arent any different to any other diesel on the road, they will run just fine on any fuel sold in the UK... The problem actually lies with lack of fuel filter changes more than anything else and also lack of servicing regularly when it comes to EGR, MAP issues.... Then also exasperated by poor re-mapping!
Again something that given the mileage that HGV's do on the road, they are in for servicing every five to six weeks, with the fuel filter changed accordingly... That's why they never have an issue with any fuel regardless of where they get it from
HTH clear up your concerns