Wow... Impressive... And certainly no sorry required. I get the process now and I must thank everyone for being so patient.
I love the phone but want to be happy that if I sell it on at any stage the new buyer won't miss out on any future updates. Someone at work pointed me at a gui utility on the xda developers forum , Hasoon2000 HTC One tool kit, that also locks the ROM. But in either case I'm happy to give it a go as it looks fairly straightforward