The great thing about Bavaria plumbing is that it is all push-fit fittings which makes winterising really easy. If you want to continue using the boat over the winter you will find as others have said that the transom shower head is prone to splitting and although you can buy new ones from Penguin (see http://www.bavariaowners.co.uk/forum/phpBB3/viewtopic.php?f=32&t=275 for details), it is by far easier and cheaper to prevent rather than cure.
On our B30 I disconnected the transom shower for the winter by switching off the water pump and opening all the taps to release any pressure, entering the transom via the hatch at the rear of the aft cabin, cutting the water supply pipes to the shower mixer and capping off just the feed side with some push-fit stop ends. (http://www.johnguest.com/part_spec.asp?s=PKM46_S1). You will get some water leak out but provided you have released any presure from the system including opening the shower tap it will be containable. After the risk of freezing was past in the spring I removed the stop ends and replaced with straight connectors (http://www.johnguest.com/part_spec.asp?s=PEM04_S1). Push-fits are designed to be able to be removed and I can see no reason why swapping during the autumn and spring should cause any problems.
If you should decide to do this, I would recommend that you still remove the transom shower head. If you do remove it, make sure that you also remove the black sealing washer from the shower pipe as it is a real pain when you find it missing in the spring, don’t ask how I know!
The push-fit fittings are available from just about any DIY store. Some, but not all fittings require an insert (http://www.johnguest.com/part_spec.asp?s=TSM_S3) pushed into the end of each pipe at every joint, something that Bavaria don’t fit. These inserts stop the pipe from deforming to help the fitting grip onto the pipe better and I have only ever seen them sold in packets.
When leaving the boat over the winter months I always leave all taps open and because they are mixer taps I ensure that the handles are in the middle and I top up the water tank to just over 3/4’s full.
One final tip, I have found that the chrome finish on the taps and lights can suffer badly over the winter, before shutting the boat up I wipe over the taps and lights with extra virgin olive oil which seems to protect them and has the added bonus that it is really easy to clean off when you return.
Hope you have some great sailing over the winter,