Funny - I was just thinking today about the possibility of crossover between the two series.
And do the characters in RaR ever watch Pobol y Cwm on TV, and vice versa....?
I can imagine it might give rise to some good "in jokes".
As to whether "Glandrafon" is really Menai Bridge (or a district within Menai Bridge), well, we know that "Cilbedlam" is really there (even if the shop etc is fake). And yes, people are always popping over to Bangor.
However, I have yet to properly locate the street where Iris & Arthur, and Meical and Michelle live. I did have bit of a look for it when I visited Menai Bridge some years ago, and have also tried using google streetview, but with no luck. If anyone finds them, please let me know!