Gemma,
The nausea is usually associated with chemo. If you are only receiving radiation then you can expect to have a few side effects with your name on them. From your description if the current cancer is only in the lymph nodes and no cancer in the oral or pharyngeal areas, then you very well might not suffer the typical side effects that radiation offers to those being radiation in the mouth or down along the throat.

For example, if the rads skirt around the parotid glands, then you saliva may be intact. That might also mean you avoid the common dry mouth side effects. Your taste may not be as affected either as the rads won't blast your tongue as much.

One thing for certain, even for people with the exact same diagnosis and treatment plan, each can have very different experiences during treatment and post treatment and side effects.

Good luck,
don