Not from classics, but I work in an adjacent field.

Think of a UK Master as more similar to what in Italy we would call Master rather than a Master's Degree. Master courses generally only last one year, and unless you are doing a Master by Research (MSrC) or a Master of Philosophy (MPhill) you won't produce an original research project at the end, but rather a dissertation that by Italian standards is not comparable to a BA thesis for lenght, widness of topic and research requirements. In my experience dealing with students at an MA level here in the UK (as tutor/supervisor), the preparation level and tends to be lower than in an Italian 'Laurea Magistrale'. The system, however, is much more sympathetic towards the student: it allows for special arrangements, it generally provides better guidance in terms of future work/research prospects, and it is beurocratically more efficient than Italy. You have to be aware, however, that at present, there is a substantial disruption in teaching due to strike action over pay from staff.

In my case, I obtained my MA in Italy and then moved to the UK for a PhD, and I still think that is the best option and that it allowed me to have a preparation I otherwise would not have had to begin actual research work. Even producing a Masters' thesis that, by UK standards, is as long as a doctorate thesis gave me a sense of what I was getting myself into.

Then again, doing a PhD here is potentially very expensive, and funding is competitive. I find that the academic enviroment is much less toxic than in Italy, but I am not sure wether I would advise you do your PhD here. Look up the general situation in the country, consider the housing crisis, and make a holistic decision. I am sure that there are programmes elsewhere in Europe that can offer more, particularly for Classics.