Disclosing to your employer is a big decision and a personal one.  If your MS is stable and symptoms aren’t affecting your work then many people may not need to tell their employer.  However, if your symptoms are starting to impact on your working day such as fatigue, difficulty concentrating, struggling with the stairs up to the 2^nd floor office then telling your employer maybe a good option.

By law you only need to disclose your diagnosis if you are in the armed forces, if you are in a driving role at work e.g HGV driver/taxi, or your MS may affect health and safety in the work place e.g. you work on a building site and are using scaffolding. 

If you are trying to decide whether to tell your employer or not then have a look at the MS Society work toolkit: https://www.mssociety.org.uk/care-and-support/everyday-living/working-and-ms/work-toolkit

They have a decision making sheet to help you note the pro’s and con’s of telling your employer and advice on how to do this.  If you do decide to tell them then this information is confidential between you, your employer and human resources.  You do not have to tell your colleagues unless you feel ready or feel it will help their understanding of why you may do things in a certain way.

This short video by Shift.MS is a great way to change your way of thinking about disclosure: