It's an adjustment, but I think the visits are important and will help keep you close.
My AH (I guess RAH now) has been in prison for 15 months now. We visit once a month because of the drive. My oldest is 16, has been once, is resentful of her father for being there and refuses to go back. My son who's 14, will go every once in a while. My youngest who's 10 and daddys girl goes every visit. I won't force them to go and sometimes it upsets RAH because they don't all come, but I figure that will work it self out since he is doing the 12-steps and will be working on amends etc soon. Sounds like your kids will be ok with the visits and the 4 months should go by quickly. Just keep the kids informed and let them know its only 4 months and how much you love and miss them.