As far as Clocaenog is concerned, you could contact Michelle Moneypenny - She is French, but speaks excellent English - her husband is a painter and decorator and they live in Clocaenog, in what I think was the old post office. Moneypenny shouldn't be too difficult a name to find in the on-line telephone directory. Michelle wouldn't know anything about the chapel I don't think, but could put you in touch with someone who could.
It is really difficult to think of the names of people in Melin Y Wig, as I knew them by nick-names - very common in Wales and particularly so in that part of N.Wales. Gwil Tai Teg isn't going to help you. Gwilym lives in a farm called Tai Teg (which means the pretty houses) I never knew what his surname was. We were known as Pook T'Isa - even the name of our house, which had been there for 400 years had been shortened from Ty Isaf (Lower House) (Pook is my married name).
Most of the people I knew by those sort of names.
What you could do would be to write to the chapel and hope that someone would open the letter and help you with information. If you could find someone to write in Welsh for you, it would be good, as the area and the chapel are almost completely Welsh-speaking.
If you can't, they can all speak English, if somewhat haltingly at times, but don't let them think that anyone said that, or they would be highly offended.
Chapel is 'Y capel', and the preacher is 'Y parch'. and the correct name of the village is Melin Y Wig. I am not sure which county it is in now, as they change so often - it used to be Merionethshire. Lord Dafydd Elllis Thomas used to be the M.P. He is now something high up in the Welsh Assembly. I never knew what denomination the chapel was, it wasn't Baptist. I'll have a look on the net and see what I can find out.
Sincerely,
Rachel Bowen