Do i actually get unlimited calls text and data on tmobile with the full monty?

I'm planning on getting the iphone 5 off tmobile and just wondering whether the full monty plan will charge me more

The full monty plan gives you unlimited calls to UK mobiles and landlines (not 08 numbers) and unlimited texts and data.
They have a 'fair usage' policy. Meaning that if your excessive use was causing a problem on the network then they could stop you using it. But this is very unlikely as you'd have to be sending millions of messages a day to cause a network problem.