In each building there are 4-5 floors, each with 1 kitchen 3 toilets and 3 separate shower rooms. Therefore there are 4-5 people to a shower and toilet. This may sound bad but each room has its own wash basin, and in your second and third year when living off campus (unless you come back to the campus for your last year) ow many do you think you will be sharing a bathroom with. Student houses are literally like an ordinary house, there will be 4 or 5 (if not more) to a house sharing one bathroom, there are no en-suits. Anyway the showers and toilets are cleaned everyday for you on campus they won't be when your living out.
Also you will only have access to your own flat therefore there aren't really 12 toilets and 12 showers to 56 people.
Side note: the accommodation will be a lot more expensive when living off campus, say £350 a month and will often not include all the bills such as electricity, water and possible gas too. So count your blessing, it doesn't sound like it but you really do get your moneys work with university accommodation most of the time.