our sick policy has been changed several times over the years, we get an email outlining the changes and a link to the online staff handbook. as TTT has said, they don't have to pay you anything other than stat requirements.
that said - out sickness policy states its down to the manager to auth the sick pay, you may find different people have their episodes of sickness treated differently depening on the situation. For example i had 8 weeks off work last year due to a major op which was paid in full, a colleague had i think 4 or 5 weeks off with a broken leg, which was'nt paid as he did it playing footie