Assuming Italy hasn't become 'JAA' since I last looked, the answer is "NO".
As you haven't got lots of real practical flightdeck hours as an ATPL/IR, to be employable by a UK airline, you really need to do:
the JAA ATPL ground school and examinations
sufficient JAA CPL training for your training organisation to say you are ready for the JAA CPL flight skills test (and then pass it)
15 hours minimum JAA I/R training and JAA I/R test
Multi Crew Cooperation Course
ps: remember you are not 'SWAPPING' your ratings and licences, you still keep your Italian ones and get the JAA ones as well.