When someone is bed-ridden, homebound, or in the hospital, Father will make a "sick call" to ensure the person receives the Eucharist - an especially important duty around Easter time (he will hear Confession if necessary). In cases of possible death, he will offer Extreme Unction (in such a situation, call Father as soon as possible, day or night!). Unction is a separate Sacrament that includes an anointing with Oleum Infirmorum (the Oil of the Sick).
For a regular sick call (i.e., one that doesn't include Unction), please call Father to arrange a convenient time. When he comes, remember that he will be bringing the Blessed Sacrament, the very Body of Christ.
WHAT TO DO IF YOU ARE IN HOSPITAL
In the age of the Data Protection Act, there has been a significant change in the information that is released to Hospital Chaplains. This means that unless you specifically request that your details be passed on to the Catholic Chaplain, then he will be completely unaware of your presence in the hospital. So, please contact the parish priest and let him know if you (or a relative) are in hospital, and he will either come himself or notify the local clergy who have care of that hospital.