Very many thanks, everyone, for all that very informative and helpful information. It has made the whole issue much more understandable. The Lenovo has quite a decent spec; good processor, plenty of RAM, so i don't think W10 should trouble it too much. The suck-it-and-see option makes a lot of sense, but I will check on the glitch with switching.
Mind you if it boots into S mode, as I suspect it might, I'll be stuffed anyway if I can't switch it to normal.