This weblink may supplement the useful info provided by bookbinder. Whilst bookbinder's link from NHS explains the general care and support options at home, this page explains explicitly what must happen as someone is discharged from hospital
http://www.nhs.uk/conditions/social-care-and-support-guide/pages/hospital-discharge-care.aspx
It aligns to what Eddie is referring to, so perhaps may be more helpful right now.
I do not agree with pixie's version of what happens - the care package is provided as a prerequisite of discharge and is ongoing. It is also free (in that it is funded by NHS or the local authority) for the first six weeks. During that time a financial assessment is made and the individual may have to fund the care package after this time. It is not an emergency package that gets withdrawn unilaterally.