Thank you sir, quick story- im down in sydney to see surgeon & rehab work placement so my pc's in queensland, friend lent me his lappy, visited maccas for the free wi-fi, it was broken down or who knows, so this morning spoke to phone com - TELSTRA about my data, 8gigs one time only $20! So..... I've done it the long way but it's now updated.Yes, wifi update will be smaller. iTunes update gets the whole OS presumably for the ability to do a total restore to your phone if something really bad happens at some point. Whole OS isn't needed for a patch, only the patch.
thanks again, no doubt I'll be asking more questions or sites to help.