I have a spider plant in my Russian's cage. They are tortoise safe and fine if they eat them although my tortoise won't go for it, he prefers lettuce or weeds.
Hi I’m in UK too. I bought a lavender plant last year, it’s more for shade, don’t think they eat them. Charlie is always hiding under it when it gets hot. I sprinkled some tortoise weed seeds last autumn they didn’t come up as good as I thought they would but even though they’re only small he does have a munch on them, don’t think I’ll ever get to see them grow with him nibbling on them though ?