According to wikipedia "Pwllheli is a community and the main market town of the Llŷn Peninsula in Gwynedd, north-western Wales. It had a population of 4,076 in 2011 of whom a large proportion, 81 per cent, are Welsh speaking. Pwllheli is the place where Plaid Cymru was founded. It is the birthplace of the Welsh poet Sir Albert Evans-Jones." The name was, and still is, well known to many outside the area because of the holiday camp which is located just outside the town. It was Butlins Pwllheli on which the TV series from the eighties Hi-di-Hi was based... but please don't let that put you off visiting the area! (The TV series wasn't filmed in Wales). The Llyn Peninsula/ Pen Llŷn is a designated "Area of Outstanding Natural Beauty".
I think I went through it on the bus, once, maybe on the way to Llandudno? I remember wishing people would slow down as they said it, so I could figure out how to pronounce it. Finally got my wish here. :)