Hi David, "how long" and "how much time" mean really the same thing when you are talking about "time". You can use either expression, and an English speaker is going to understand what you're trying to say, no problem. But sometime "how much time" will sound a little strange. I think you can always just say "how long" when you speak English, especially while you are learning English. For example:
1a. How long have you been learning to speak English? - GOOD
1b. How much time have you been learning to speak English? - NO (awkward)
2a. How long do you think this doctor's examination will take? - GOOD
2b. How much time do you think this doctor's examination will take? - OK
3a. How long did you live in Australia, before you moved to Canada? - GOOD
3b. How much time did you live in Australia, before you moved to Canada? - NO (awkward)