How much have you traveled together? Have you camped in an RV with your kids?
Here are my thoughts:
-Traveling tends to add stress to a relationship, not relieve it.
-Some kids travel well, others don't. Have you traveled enough with your kids to know? I've got one kid who's a great traveler, one who needs to go home after 2 weeks. (We just got home after 2 weeks + 2 days away. The last 3 nights, dd was sobbing in our arms while we visited relatives because she was out of sorts. Really, she just needed to go home. It'll take her a week to get back to equilibrium.)
-A 1 year old and 3 year old (or 2 and 4) aren't really old enough to appreciate all of the things that you're going to see. 8 and 10 or 10 and 12 would be much better ages for on-the-road learning.
-Furthering his education is something that I think makes sense.
-Looking for a new job where he feels less stressed makes sense (especially if it's closer to family that you'd like to be near)
-Doing a trial run makes sense -- could he take a couple weeks unpaid leave + vacation and have you travel for a month next summer? That will tell you whether you can handle it for a longer period. (A week isn't long enough, and not even 2 weeks.) If that works well, then maybe a year does make sense.
What are you doing now to strengthen your relationship? Do you have babysitters you can pay to sit with your kids (in a few months' time, if you've got an 8 week old) so you and your dh can go out and reconnect? Sometimes just going to dinner or walking around a lake helps.
What are your husband's skills and job prospects? What are yours? Maybe investing in a career counseling would be a good idea for him.
It sounds like he's unhappy and fantasizing about things being completely different. If you take concrete steps toward them, and think it'll work for you, OK. If he's willing to plan and do some of the hard work to get things going, that'll tell you whether this is a fantasy or something that will really make you both happy. I would love to spend a year traveling. But, right now, it's not going to work with our lives. I'm OK with waiting until the kids are in college and I'm retired. Some people wouldn't be.