1.I am used to working in Excel 2000. I have not worked on the new version of Excel.
- sounds fine the way it is -
2.There is one and a half hours drive from Dubai to Abudhabi.
Perhaps better as: "It's a 90-minute drive from ... " or, if you need to say it in another way, "It's a one and a half hour's drive from ..."
The hour needs a possessive 's in the second example. You don't need the possessive if you use the time as an adjective, as I did with the first example.
Note, however, the dash between 90 and minute, to clarify its use as a compound adjective, not in the possessive. Similarly, you could use the even more cumbersome, "It's a one-and-a-half-hour drive from..."
3.I had no option left with me, but to accept the offer.
"Less is more": I had no option but to accept the offer.