When purchasing a complete tv series with say 6 episodes, is it possible to download half of them straightaway then the others at a later date?

Thanks

Why would you want to do this? Are you trying to save hard drive space or have another reason?

Is it cheaper to buy the whole series than each episode as and when you need them?

Are you planning on watching on a computer or ios device?

I think with the latest ios update you have a purchase history in itunes via an ios device. so you can download a video and delete it from your device and should you need it at a later date then download it again.

The best course of action would be to download all of them via itunes on your comouter then sync them up to your device as and when you want them. I don't even think you'll need to sync them once they are on your PC as they would then show up in your purchase history would it not?

I've not used the new cloud based features as I'm jailbroken on 4.3.1 so not running the latest update and dont have access to them on my iphone. I also don't buy any videos through the itunes store, so I can;t really verify that all these features are up and running yet (they should be fully working for ios5, but a cut down list of cloud features is active now).

Yes it is. Buy the series on your PC. Start downloading them. Then click Downloads in the left menu and it should show you a screen of the items downloading. Next to each of the items there should be a little x on the right hand side. Click it for the items you want to download later and you'll see a Resume icon appear instead. When you're ready to download the rest, just click those.