Sorry about that, I was on my phone.
Right. Yes, as above get Clipper Green Tea which is decaf. It's the nicest green tea I have had yet.
With regards to the Diet Coke, don't bother drinking drinking that just to cut out caffiene. It's full of all sorts of nasties, you'll be doing yourself more harm than good.
If you really must drink cola, then drink the 'full fat' version. It's all horrible, in my opinion, but stay well away from the diet drinks.
I once had a really nice can of 'organic' coke. Think it was called something like whole earth? I'm not really a big fizzy drink lover (too much acid for me) but this was really nice.