A complete bike will be much cheaper than putting one together from spare parts, although if you bought the frameset and all the parts at the same time from an LBS I'm sure they'd give you a better price... but still...
If I was in your socks (cycling shoes
I'd buy a complete bike and then practice taking it to pieces bit by bit with the tools I had, then putting it back together again. The correct tools to completely build a bike are going to be fairly expensive, but with tools you'll need (and can carry) on the road you can take the bike down to frame, fork, bottom bracket and headset.
There's great info to be found on the net (start with sheldonbrown.com or just google) on all things bike, the mechanics forum here is a great resource if you get stuck.
Then once your done practicing, take the bike back to your LBS to tune it up and check that you haven't done anything that could potentially be dangerous or damage the bike when you set off on tour...
Do you have a knowledgeable friend who can help?
Good Luck!