Lack of internet access
I am going on holiday for 10 days and will not have access to the internet. I usually study Duolingo every day. I am equipped for a one day gap but is there anyway I can protect my progress for longer on this one-off occasion
Your progress is fine. You're at level 23 in Spanish right now, and you will be when you come back - that's just based on the number of points you've accumulated and has nothing to do with your learning. Your streak will end, but don't worry about it. Your vacation is more important than pixels on a screen or the accumulation of useless lingots. You'll be fine.
I have been studying on Duo for a few years now, and have lost large (200+ day) streaks a few times. It's not really a big deal, we are here for the knowledge after all.
As stated your level will not go down and if the streak is that important to you just set your difficulty level at the easiest and have someone you trust log on and do a lesson or buy a streak freeze every day.