Can anyone tell me if it's ok for my Greek Spur Thigh to eat what we commonly call 'spider plant' please?

If you're speaking of the houseplant or garden plant (also called spiderwort) , both are fine.

I was speaking of the houseplant, thank you very much, I can't get over how responsive you all are on here, I guess it's because you really love tortoises and love to help. I can't wait until I am in a position to give some helpful advice on our little friends.

O.K. here is another question for all of you Tort/plant geniuses.
is there things to look for on or in a plant that lets you know it is safe or not?
otherwise how do you know if something is safe for the tort to eat?

Well among the sources I check are USDA PLANT lists, Various state extension forage lists, natural history studies on various species (field study treatses), personal observation of native turtles (unfornately I have never lived in an area with torts), and thirtysome years with a trio of RFs as instructors. I also pick the brains of fellow keepers such as you are doing and talking with neighbors who's experience with the the enviornment in several cases goes back or went back to the turnof the last century (preTV ).