hey thanks for the reply and sorry for the really late reply on my behalf looking at the actual cassette its an SRAM 40Nm im reallly new to all this so im sure ive more than likely found the wrong info
looking at the actual derailleur it looks to be fairly long compaired to ones ive found browsing around, my biggest problem seems to be that all road ones ive found dont go to 8speed that all seem to be 10+ more than likely because my bikes hitting about 3 years old now, the front gears are 2 chainring along the front although at closer inspection they seem to have gone from round to rugby ball style shape :S so i might have to replace that as well