I know you are all giving me advice and it is much appreciated really!!

I have the flights all on one segment. I have called SAS and they told me that I can pay 60 Euro to rebook. So surely if I am at Gatwick and it looks like I am missing my connection I can call to rebook before they cancel my entire journey? Would that be a lower risk?
Also I was checking I could STD - Frankfurt Hahn then take a bus.