For the iPhone 4 and iPad. If you buy one contract free they will offer you a cheap contract. At a later date, when they can get them in stock, they will give you contract prices for them.

The only down side is that the iPad contract (data only) gives you more data for your £15 (10gb vs 5)

1. Can you actually use it as a plain phone?

2. Can you use it as, say, a wireless or Bluetooth shared internet connection for other devices?