I think a break away is invaluable, but when you take it is the problem.
If you are not working and you are flexible I'd say leave it a few weeks. If you have no choice, take what you can get.
You can reasonably expect to have some skin issues after radiotherapy, most of the time they resolve within a couple of weeks. If you are in any way comprised before you go into that phase of treatment you could need some extra help. Most of us get kicked off the bus after rads and don't have any follow up, but I wouldn't want to be chasing help while I was on holidays.