Luckily the digitizer still working and the serious cracks not really reached the screen itself, apart a small fracture from the clock area.
So, I decided to repair it somehow DIY, because a proper screen-repair could cost you around 120 GBP.
Step 1: Clean Up the Mess
some used top-up or sim-card
pen or pencil
clear liquid glue
Black acrylic paint
a bit of developed 35 mm film negative
good eye for details
iPhone screen protector (optional)
Firstly I removed the broken glass chips from the seriously damaged area with a tweezer. Under those there are the speaker and the light sensors.
I fixed the remaining shivers over the clock area with a model-kit glue,because I want to see the clock.
Step 2: The Right Shape
I used a transparent piece of plastic (or it could be a paper too) to get the guideline to cut the plastic-card for the right shape around the crackline.
Check how it fit after every cut! Use sandpaper to shape the rims of the corners. Then carry on until everything is just fit.
Step 3: Holes
After everything on place get a small bit of an already developed film-negative. It is a very cheap IR-filter layer solution. For a proper working proximity and light sensors it is necessary.
Put that piece of film under the top-row holes (do not cover the speakar holes!).
Step 4: Matching Color
Step 5: The Last Layer
I have to admit this is not an ultimate solution, but will be ok until I get a faulty iPhone with an intact screen