British English - “In two hours time”

I would agree that the use of the extra word "time" in your example adds nothing, and is therefore redundant and better avoided.

To my British ears, this usage sounds more American! Maybe it's just as incorrect on both sides of the pond...

For the duration of an event, the word "time" would never be appended in English: "He has a class for 45 minutes", (although it would in some other languages).

The 'time' bit is redundant even in British English. It's possibly technically more correct but sounds a little stiff or old fashioned, anyone would understand "in 30mins"

edit: there are possibly occasions where you would need to differentiate between minutes/seconds of time and minutes/seconds of arc - but unless you are writing astronomy or navigational software I wouldn't worry.