The DfEE publication Supporting Pupils with Medical Needs and Circular 14/96 are good references. It is also worth contacting the Health Education Authority which publishes all sorts of useful materials (e.g. The Use of Sunscreens in School: A Good Practice Guide). Most medical conditions have an associated support group. Advice about communicable diseases is usually obtainable via your local Health Authority’s Consultant in Communicable Disease Control.