Be Honest About It
Working from home is undoubtedly a challenge if you have never done it before. It can be a grueling transition from one environment to another, and that can make you feel stressed out and aggravated. Even without children and added responsibilities of working from home, you may find yourself more tired than normal or find yourself procrastinating even as deadlines close in.
Aside from being honest with your partner about the difficulties you are having, talk to your children about it too. Let them know that you are busy and will need them to behave or help out when they can.
Next, be honest with your employer. Tell them ahead of time that you may be disrupted by your kids or have to run out of a meeting on occasion. Chances are that your employer will understand exactly what you are going through.