How much internet data does the average person use?

Me and my Dad have a caravan at the seaside but we don't have internet access in the caravan (apart from our smartphones).

I have an iPhone on contract with 10gb per month data allowance, and I've just found out that I can use my iPhone to create a personal wi-fi hotspot. I was going to do that so I can use the internet on my laptop at the caravan, but will I be in any danger of using all my data allowance if I do this every weekend?

If you only check emails and facebook then you will be fine. If you look at pictures and video there could be a risk that you will go over your limit. Get one of those apps that monitor your data and remember to use it.