Ill post up a few photos of the process (I did) to smooth the bumper I'm not 100% happy with it so ill be redoing it soon. if you do this I suggest you check then check then check again that it is 100% smooth before you paint as mine isn't perfect and I'm going to have to start again may be me being fussy but ill be redoing it next week.
I got the bumper filler from halfords £8 a tube and I used 2 tubes
I cut 2 pieces of Perspex to the same size as the number plate 1 cracked but I just put it under the other one and screwd them into place you can also use spare trim , this is to take up most of the space so you don't use so much filler (most people say to plastic weld but when your slapping on so much filler it doesn't matter to much as this filler is more flexible than standard stuff so won't crack
Then bacicly fill it sand it and paint it really lol use a sanding block the so you take the shape of the bumper. Hopefull the pics will speak for themself.
I have made this sound like a easy job but it really isn't it took me 2-3 days and sanding until my hands were bleeding but its worth it in the end.
And before anyone says it I know it's good to have a bathroom that doubles up as a garage lol
I also fitted fog lights and sprayed the fog surrounds and bumper grilles gloss black
Hope this helps someone :)