Thank you all for your advice I think I have it covered now except for another question regarding the external hard drive.
On starting the File History backups (and they seem to be residing together on the same external HDD, at least I have not been warned of overwriting so far) I realised that the external hard drive was closing down when I shut down the PC. On checking around I found that in device manager I could uncheck the power options for the USB. Fine, now the external hard drive stays on when I shut down. But.......when I boot up the PC the external hard drive switches itself off. Does this mean every time I boot up I will need to unplug and plug on again either the power plug or the USB that connects it to the PC, and should I have left the drive to turn off when shutting down anyway, (heating problems)?
And how often does MS release a new build?