The best people to ask about these questions as we are not medical professionals on this forum and your consultant and specialist nurses will give you definitive advice. My brother had brachytherapy and recovered well within 3 months although did have urination problems for about three weeks. As for going on a flight 6 days after the test I would imagine that would be OK so long as you are not having any side effects from the general anaesthetic or urinary problems - in which case you may have to try and get a seat near to the lavatory and/or wear pads - where are you going and how long is the flight might make a difference.
I think you would have to wait a few weeks before going on holiday because you are told not to go too near young children for matter of a few weeks due to the radiotherapy being omitted from the seeds - but I can't remember how long - when I say near I believe they told my brother not to cuddle his little grandchildren or sit them on his lap for a couple/few weeks. He was more concerned about his dogs than his grandchildren. Remember that during the first few months you can get side effects come along at odd times as the radiotherapy works so ask about that too. Again it all depends on the length of the flight - especially if you are having urinary problems as the same will apply as above. 3 nearly 4 years later my brother is fine and his PSA is undetectable. Please ask for advice at your hospital about this as guidance may have changed considerably in the last few years.
Hope someone who has had brachytherapy here comes along soon to give you a better reply from their own experience.
Thanks for the reply it's appreciated.Got diagnosed nit long back and I'm fit and healthy 63 year old.All is moving really quickly Which I'm happy about.The breaks are all cancellable or covered by insurance so it's not an issue not to go.Just due to covid we moved all the breaks to this year.
