Easy enough.
1. Remove trim under head lights. Inside edge first (plastic rivets), then un hook outer edge.
2. Remove plastic rivets from top of bumper, between lights.
3. Remove 4 torx screws, (2 each side) from wheel arch edge of bumper.
4. Under bumper 4 more clips/ screws, (can't remember which).
5. Unplug foglights.
6. Pull bumper shell off.
7. Disconnect headlight washer pipes (if fitted), and unplug air temp sensor.
8. Move bumper to one side, and lift off polystyrene moulding from the crash bar.
9. Unplug washer pump(s) and washer level sensor.
10. Un bolt crash bar from brackets and remove.
11. Washer bottle held onto crash bar with 4 screws.
Refit as dismantled.
DO NOT remove the crash bar brackets from the car as, (imo), they are a biatch to set right. If your bumper is a good fit, then leave these well alone! If you're replacing the bottle through accident damage then brackets probably bent so removing not an issue as will need replacing.
All in all a straight forward job. It took me longer to type this with 2 fingers than i takes to actually remove the bumper.
HTH, Al