(I do hope that’s not a serious question…
why would Handel have been in a pub (or one where there was any traditional music, which was associated with the poor Catholic Irish at that time)? and the Irish pub session is actually a relatively new thing, playing used to happen largely in houses. )
Handel spent some time in my local ‘The Yacht Inn’ Wirral Cheshire England.
He spent most of his life living in England and even became a naturalised Englishman.
On his way to Dublin for the first performance of the Messiah (In Temple bar) he was delayed for days in The Wirral near Parkgate ferry port.
The weather delayed the sailing. Some say he took a coach to Angelsey in Wales for th shorter ferry sailing.
He would have spent some time in local hostelries during that journey. (100 miles by coach).
MAYBE 
travelling Irish folk entertained him with their pretty tunes.