How much does it cost to repair a shattered iphone 4 screen?

My iphone 4 was smashed hard as it fell from my window onto stones! The phone works PERFECTLY! I'm actually using it now to write this. But its very hard to see and i absoloutly need it fixed as it is EXTEMELY broken. How much in POUNDS would it cost on average? And is Apple cheaper? And should i get a diy kit? Please ANSWER As soon as possible!

Buy a new one

You can order the DIY kit plus you get the instructions for £5 plus next day delivery and you get the screen for around £10 much cheaper than playing in a shop to get it repaired which is about £40-£50, I know it sounds complicated but it is alot easier than I'm making it out to be