Depends on which MBP you have. The older ones are relatively easy to do a self-service panel swap. iFixit has really nice guides.
https/www.ifixit.com/Device/MacBook_Pro
https
/www.laptopscreen.com/English/brand/Apple/
The newer ones I believe use adhesive to hold the screen assembly together. To swap the panel, you have to use a heat gun or (if you're really patient) a hair dryer to loosen the adhesive.
I'm guessing 450£ is probably the price to swap the entire display assembly (the lid portion of the laptop). If only the only problem is that the screen is broken and you're skilled enough to do it yourself, you can probably do a panel swap for about $150. You might want to check iFixit's tool store for any special tools you'll need to disassemble Apple's hardware.
thanks a lot for your answer but I don't know if I can manage it and I find it quiet risky so I was loooking for somewhere that you would suggest me to go it that would be cheaper