There is not enough space to give you the help you need and time is another issue altogether...
You will do best to give the matter some thought and call a bathroom specialist - for instance do you want a shower enclosure with a shower tray to stand in or do you want your shower over an existing bath? Are you planning to have a pumped shower or an electric shower - do you have a boiler and what type? How much have you got to spend - whatever the answer is, it will always cost more than you thought.
Good luck...
Peccavi
September 2009