My only saves are in the final battle so therefore i cant play the Dlc!!!! why wasn't the Dlc a follow on it would of made for sense!!

It's been stated that there is a definitive end in FO:NV, so don't get your hopes up for that. Also, it says in the game when you reach the point of no return. Seeing as you have to return to the Mojave in order to start Dead Money, that makes sense too. If you don't have another save you can just start again with a new character - and luckily the game is really good so shouldn't prove too much of a grind!

[Edit]: Just thought I'd add that when you get to the DLC starting point, it advises you to be at around level 20, so I wouldn't start a new character and go rushing there if I were you - unless you're up for a real challenge.