So I wondering if the fiesta ST has the same body shape as the standard fiesta, only ask as I'm wanting to fit a M sports WRC kit to the car, they use a fiesta st, so I'm wondering if it'll still fit. 

Are you saying just the body? As I assumed the M Sport WRC was a 2013+ 380bhp beast with custom body and rollcage and much more. However because of how much is changed in the kit, I assume it's all new panels/bolt-ons, so it doesn't massively matter about the "shell" beneath it, most variants of Fiesta are pretty similar, and if you're wanting to spend that much on a kit, I'm sure a little extra can be spent to make sure it all fits together. 

Is this just for a project/bit of fun? Or looking to kit it out? 

Your 2012 will be a pre-facelift Mk7, so different bonnet, lights and front bumper. Some people call the ST a Mk7.5 because it's a post-facelift Mk7. No idea if that would affect how the body kit fits though. 

I'm looking to build the car bit by bit, but, I don't wanna cash out on a ST if the kit will already fit the car, I mean I'm not looking the enter the car into any races but I want a as close replica as I can get, with out spending the 300k plus on getting M sports to build me on. 

The ST has a different front end to the pre-facelift mk7 (as said above). Replicas suck though. I've always said don't try and make your car look like something it isn't. By the time you've farted around with a bodykit and everything else to make it look exactly like an ST, it would be just as cheap to buy an ST.

Pretty much what Luke says. For 8k~ you could get a 2013 ST, remap, bodykit, and have a nice looking car with 200+bhp for no more than an extra 1k. 

Unless I've got it wrong, these types of kits are looking to be 2-3k. And that's just the look, if you start going for performance, that figure will more than double.  I'm all for having a project car, something you can modify and call your own, but just know you're gonna get a lot of...feedback when you have a rally car that moves like my nan's fiesta. 

In any case, if you do go ahead with this, I look forward to seeing the progress.