Well I do like cheese so I'm really tempted to go for it.
I've already done a full Macrium Reflect backup image and a Rescue Media thingy (which I've checked DOES boot up my PC to the Reflect program OK) on an external hard drive so theoretically I'm good to go BUT I want a clear run at it allowing a couple of hours (or more??) so still reading/checking stuff out before I jump!
Thanks for all your help & suggestions so far.
Anything not mentioned in previous posts that I really do need to be very aware of??