First thing I would do is figure out how much data you use in 30 minutes live feed ,
there are apps for that , or go to settings and check data when you start and finish ,
Then you will know what you need ,
And if your followers are in the USA are you trying to give them the 20-40 minutes at the same USA time everyday ? You may be able to record daytime Europe time and upload later on WiFi
From what I have read .Three UK uses a lot of 3g on the continent . Will that be fast enough ?