Sorry for scaring you guys with that pic but it is easy enough to get bumper off:
1. Remove lower bumper screws in wheel arch (mine were very rusted-lots of plus-gas needed)
2. Underbumper (why i jacked front up) prise out centre pins and remove clips holding bumper.
2 1/2. Remove Front Grille
3. Unscrew headlight surround (torx bit req)
4. Unscrew bumper inner screws (behing headlight almost)
5. Unbolt bumper upper mounts (in wheel arch - M6 i think :-/)
6. bumper should now lift away but you'll need to unplug wiring to fog-lights to fully remove but they're only multi-plugs.
7. Inner bumper reinforcing bar is held on with 4 bolts and the washer bottle is inturn screwed into back of this.
Now fit your new big 7L washer bottle. obviously screen wash pump fits as before but you'll have new pump to route to headlights.
Washer jets are bolted to a bracket which is screwed to underside of headlight.
Refitting is reverse of removal

but you'll need to fit new headlamp surrounds (or make hole in your old one) nozzle unclips from end of jet so you can push through surround hole and jobs a good-un
