Phil,
Unlike the clarinet, the differences in fingering for the flute are relatively minor until you get to the extreme upper register.
I taught myself to play, borrowing one from a friend when I was about 12. The obvious difference is the embouchure - (if you can make a sound blowing over a beer or soda bottle you'll be fine) and I was pretty light headed the first couple weeks or so - no stopper for your "air".
The other bonus to picking up flute and/or clarinet are the increased opportunities for doubling in jazz bands or pit orchestras (my favorite). You're right, the portability is great for travel - grab your flute case and head outside (I like to sit by the lake) and play.
I still use an oldie but goodie Gemeinhardt, but I know other flautists who like the Pearl, Muramatsu, Miyazawa, Yamaha, or Burkhart - there are many options out there now - see if you can borrow one first from someone you know just to try it out. I'd avoid the open key hole models in the beginning - but that's must me.
The other reason I picked up the flute - to play along with Jethro Tull albums
Give it a whirl!