have you a solicitor? talk to him/her for advice.
If not, how did they get all your reports? On what basis did you hand them over?
The Defendant (your employer) is entitled to have you medically examined, with your consent. If you do not consent, then they can go to court to apply for an Order compelling you to submit to examination.
The examination will be thorough and the examining doctor will consult with your doctor before submitting his report. The purpose of the consultation with your doctor is to get his/her opinion on the injury.