We just recently had an article in our newsletter about distractions, and kids were of course one of these points. Here's that small part of that newsletter:
"- Separate Business & Family
Let your children know you have work to do during certain hours, and DO NOT feel guilty about it. You work at HOME and being in the same house with them at all times is a huge deal. Should an emergency arise, you are right there for them. Summer can be difficult to work around, but once school starts it becomes easier to work in the day with the older children in school. "
I realize that may not be much help, but the bottom line is you shouldn't feel guilty about saying "I have to work right now, but I can play in an hour". I believe it's better to know you are there and WILL be ready to play in just a short amount of time instead of being stuck at work for an undetermined amount of time.