Smart plan 300 unlimited data (24 months)
£18.00 monthly
Includes
unlimited data allowance , 300 Minutes , 1000 Texts
One of cost for £50

T Mobile says I can upgrade on the 14th so does this mean I can leave next month?
If I want the above?

That's Good.
Last time I looked even Tesco was £21.00.
You can upgrade 1 month before. If you want to leave let them know 1 month before too.
Check the unlimited data. probably capped at 500MB.
But that's enough if you don't stream video or radio or download lots of music. Do that at home in wifi land. Find an app to show your usage.
A fine phone too.

I saw that to and I think it only had 100mb or 500mb with it.
I know the S3 is coming out soon but I am not looking to spend no more than £20 a month.

Yes, I am paying £19 for 300 mins and only 500mb data.

So if I get this I just need to ask T Mobile for a PAC Code on the 14th?

Looks good to me, if there is enough talk minutes/texts: beware,it could get pricey if you go over the limits of the plan. My advice is firstly to check coverage on the network(you didn't say who it's with), second to check their over-limit costs,and thirdly to Ring TMobile's C.S on the 14th,that's when you can give 30 day's notice to finish. It's also when you can negotiate a new deal:Tell the upgrades team what you want them to beat.

If TMobile can't beat it, then go for it. (And I work for TM!)

I still have not got this yet but just phoned T Mobile and for me to get a Galaxy S2 or a Lumia 800 they want me to pay £36 + £200 a month LOL so now have to look else where.

You have to get in quick.
Try them again.
Otherwise £26.00 elsewhere. Capped calls/texts and data.