That recipe appears on several other websites, where 'T' is replaced by 'tb'. Hence it must mean 'tablespoons'. e.g:
http://www.therecipes...rs-in-pineapple-cream
I agree that 2/3 means two thirds.
A bit of googling suggests that a UK cup is a bit bigger than a US one. Just over half a UK cup (five ninths if you're being fussy) seems to be the same as two thirds of a US cup.
Chris