Will the Battlenet client install original wow BC and WOTLK I already am upgraded to WOTLK however i want to install on a new laptop so will i only have to install that along with patches

When you install the WoW Client from your battle.net account, it will install the full game. Once you start it for the first time, it will also download and install all required patches.

Note that it is also possible to copy an existing WoW installation in its entirety from another computer to your laptop (meaning less time spent and your addon/macro settings remain intact) because the game does not entrench itself in the Windows Registry.