Change address during the PhD

Dear all, I would be grateful if you could clarify me an aspect relative to changing address during a secondment of 9 months at the end of my PhD (ITN-H2020-MSCA-2014). At the moment I'm doing a PhD in Milan (Italy) and I will spend the last 9 months of my PhD as secondment in the UK, that will be spent between Sheffield and London. Since after my PhD I will permanently move to the UK,clearly is not convenient for me to pay for a rent in Milan. Does someone know if I can change my address to a city in the UK? Thanks, Susanna