Radiotherapy - breast and lymph nodes - what questions should I ask?

Hi!
I had left side radiotherapy including armpit area (I had to have complete clearance as it had spread). I had a course of 15 days.
I found the oncologist and the radiotherapy teams really helpful and informative.
Skin irritation is likely going to be an issue, and mine was pretty bad. I spent a fortune on fancy creams which I’d heard about but you know what worked best? E45 cream! I kid you not.
In hindsight, I wish I’d asked more about afterwards. How long is it still working for in my body? When is peak? What should I look out for? What’s normal skin wise and what’s not?
Also, prepare yourself for absolute elation when you finish your last one, and you get Booklets about how you’ve finished your cancer treatment! Then suddenly, after rushing around for radiotherapy and scans and appointments….you have nothing. Although that’s positive, it’s a big adjustment and can be the time when feelings catch up with you. All perfectly normal, so just make sure your nearest and dearest are aware and can support you. I put on a brave face and hid all that and it probably did me more harm than good.
Wishing you all the strength you need for this next step xx