True. Although if I launch iTunes and check for updates within the software that also says 12.3.3 is latest version. I didn't think that part was ever affected - even though it does then re-direct to Apple Software Update.
My apple software update has never glitched on me, I did see problems for others but through recent versions it's always been fine. Am keeping fingers crossed it will do the job this time too. I'll keep checking it periodically and if it doesn't appear by tomorrow I'll follow the link to do it. I presume if you do it this way you can just install over the top of existing iTunes? I would be a bit nervy about messing up my music library