I think you're very lucky to have Welsh and Sardo ancestry. I really hope you can get to the isalnd of your paternal forebears.
Unfortunately, I have been retired for many years and the visits I made to Sardegna were organised by the British Council or my office at Prifysgol Aberystwyth for academic exchanges.
However ....... I am still in Christmas-card-contact with my energetic friend in Cagliari whose efforts for Sardo-British liaison and cultural exchanges earned him an MBE from Principe/Tywysog Carlo. We have visited each other socially and "officially" on a number of occasions and I still count him as il mio buon amico Sardo
If you are thinking of visiting, I would be delighted to put you in contact. Like you, he is a teacher of second language and I feel sure he would be interested to hear from you. If you tell him a little about your father, he may even be able to suggest good places to visit.
I think Easyjet and Ryanair both have direct flights to Sardegna from UK or, if you like a little more comfort, there are many options via Rome and other European airports.
If and when you intend to go, please send me a private message via this forum (in Welsh, if you want) and I'll be delighted to contact Franco on your behalf.