The "dh" is silent and in this case I would say the "bh" as silent too. So Toor-a-lock - same or similar to
Turlough.
I dislike both
Turlough and
Toirdhealbhach. I would be surprised to find
Toirdhealbhach used nowadays - it's mostly an historic spelling.
Turlough is rare enough as it is. I googled it and didn't find any modern Toirdhealbachs - most of the references are to the famous harper
Turlough O'Carolan(Toirdhealbhach Ó Chearbhallán.