Although there are devices that are relatively easy to install in the system, try this as a simple solution to your
water hammer... Turn off the house water supply at the entrance it makes to your home. Then, go through the house and open
all of the taps and flush all of the toilets (I'm in the U.S., you call them loo's, no?). When the water quits running from the remaining pressure trapped in the lines, reopen the main water supply and, one by one, close all the taps. Hopefully, this will trap some air in the lines that will provide a cushion and should stop or at least help the banging. This will probably help for a few weeks or so and then you'll have to repeat the process. The best fix, as stated, is to install a hammer arrestor in the system... see here for a simple install:
http://www.accentshopping.com/product.asp/&P_I D/152354 , or here for a more complex install:
http://www.diynetwork.com/diy/hi_plumbing/arti cle/0,,DIY_13929_2664360,00.html ... Best of luck!