Here is the Manual:
See Page 55. It is not a real easy replacement but can be done by a first-timer if you follow the instructions.
The Part number for the U.K. keyboard is:
584161-031
U.K. ebay has lots of German and U.S. but no U.K. keyboards right now.
H.P. is also out of stock. In case you are interested here is a U.S. English keyboard:
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