Mr. Tom“The two pronunciations for the word opportunity [oppor-too-nity and oppor-chu-nity] are available in English Pronouncing Dictionary by Daniel Jones.”

Are you saying that Daniel Jones does not even mention the "British" pronunciation you see in the following link? (I would find that hard to believe.)
http://dictionary.cambridge.org/define.asp?dict=CALD&key=55715&ph=on
Cambridge represents the pronunciation of the third syllable phonetically as "tju", which is exactly the sound I was talking about when I wrote "tyu". To me, there is very definitely no CH sound there -- the "tju" pronunciation would have a T sound followed by something that sounds like the word "you".
I guess I just can't fathom anyone saying the word "opportunity" with a CH-sound rather than a T-sound.

EDIT:
I can imagine describing the "tu" part of the word "fortune" as having an initial "ch" sound, but not the "tu" part of the word "opportunity".