Hi Cheri, welcome to our family, we're here to help. I'll sound like a broken record if I say that everyone reacts to treatment differently. Okay, I said it.
I found that it knocked me for a loop. Like you two, I'm self-employed, so I simply told everyone I was taking a leave. Not good for the finances but by about week 3 of RT I could barely sit upright for more than 20 minutes. I don't say this to scare you (see my first graf), just reporting my experience. I suggest you play as it it goes.
Assume that your husband has had his pre-rads dental checkup. It's also a good idea to get a thyroid reading now. I did not know to do this and, as often happens, the radiation zapped my thyroid so like many of us I'm now on medication.
Please keep us posted and ask any and all questions. With you by his side I know your husband will get through this!