In my experience, homeworking and parenting mix about as well as coffee and olive oil. However sometimes there is no alternative and you've just got to go ahead and bite the bullet. Some, fairly obvious but nevertheless welcome, tips on how to childproof your home office here (including the fine advice to get down on your hands and knees and crawl around to get an idea of what's in most need of protection). There also seems to be a web site Parents Home Office but it's not opening at the moment.
There's a fuller, and I think much better, piece at Blue Suit Mom. Her 7 main tips can be summarised as
1. Set office hours and stick to them.
2. Close the door and walk away, or put up a decorative folding screen to block the view of works in progress.
3. Establish boundaries: create a "do not touch" pile or "do not enter" zone in your work area.
4. Create phone rules
5. Assemble a quiet Activity Box during special times such as phone calls, writing time, or during times when you need to really focus on your work.
6. Use Kid Multiplication when all else fails: give them 10 and get back 20.
7. Work WITH not AGAINST your kids' schedule by utilizing naptimes or when they are in school.