Unfortunately the UK National Archives do not hold many personal records pertaining to Italian prisoners of war as these were transferred to the Italian government after the end of the war, to form part of the man's service record. However quite a few Italian POWs opted to remain in Britain after the war and for men in this category, records are held in HO 405 and are searchable by surname.
Finally there are some interrogation records relating to Italian POWs, held in WO 208. That said many Italian soldiers were not interrogated unless they were fairly senior officers or were captured in circumstances which made them particularly interesting to British Intelligence. The records in WO 208 have not been digitised by name and so you would need to visit Kew to check if your man was interrogated. And even if he was, it seems unlikely that the reports would go into much detail about his family or his life before he joined the Italian Armed Services, so probably not worth the effort.
There is a
TNA research guide on the subject, and also a video explanation of what is held
here on Youtube. Skip forward to 11 minutes 16 seconds.
