Hi, yes they're both fine as is the sweetener as long as it's a tablet one. Redbush tea can count towards your daily water allowance as it's not a true "tea" as such. Green tea doesn't count though as it is a normal tea and therefore a diuretic.
This is one of my big bug bears. It appears that only redbush can be taken as part of the water allowance (as you say Serena), though I don't have a clue why.
Tea and coffee aren't diuretics. Well, coffee can be mildly diuretic if taken in huge quantities, but otherwise, it isn't...which means it must be as hydrating as redbush.
In fact, in normal circumstances, both tea and coffee are said to be as hydrating as water and can be used for daily fluid counts.
Have no idea why they aren't allowed instead of water on Cambridge, and look forward to the day when Cambridge include them.
Until then...officially, only water or redbush
Oh, and while I'm grumbling
I hate the advert where it using the word 'hydrating' as a selling point. Of course it's hydrating. Most drinks are! (except alcohol). Grrrrr