In fact, the Education (School Premises) Regulations 1999 (SI1999 No 2) took effect on February 1 and one of the changes is to requirements for medical rooms.
The current requirement is that every school maintained by a local education authority, and every grant-maintained school, must have accommodation for, as you say, the dental and medical examination of pupils, and that it must contain a washbasin and be reasonably near to a toilet. However, the requirement that the accommodation must also be available for the care of sick or injured pupils has been extended so that it must be available outside, as well during, school hours.
The change reflects the fact that pupils may need medical accommodation outside school hours while, for example, they wait for parents to collect them, or that such accommodation may be needed during out-of-school-hours activities.
The department intends to publish guidance to the regulations, replacing Circular 1096.
Paul Walker Department for Education and Employment, London SW1