From underneath there are 4 bolts on the crossmember to be removed (Well 2 removed and 2 slackened..) and then at each corner there is a black plastic clip which you need to turn 180 degrees(ish). The bumper should be free all you'll need to do is pull/ push it forward. The washer bottle will still be connected so you wont have that much flex untill it's disconnected.

You can also remove the small bolts under the front of the bumper, to the left and right hand side of the number plate, underneath will be 2 holes and these are used to adjust the height of the bumper, it can be done this way but I'd suggest you don't as those bolts are almost impossible to get back in