I had brachy after my hysterectomy, that was the only radiotherapy I had. I had the 5 minute version, literally was so easy! They insert the tube thing, roll some radioactive balls down it and it takes a few mins. No pain at all and I had no side effects at the time. I had 3 sessions,mine a week. Be warned they will recommend you use a dilator afterwards, I was told indefinitely. It’s not fun but it’s not a big deal, in the grand scheme of things. I occasionally bleed now after sex due to radiation damage but there’s no pain at all.
Good luck, I hope it goes well for you. My consultant said they often use just brachy after womb cancer and it’s just as effective as the full radio, without the side effects. You can also have full radio at a later point, if you need it.