You can certainly ask for these things as a right, I'd try a phone call first but if you have problems switch to Subject Access Request which is a legal request for the information.
The Med-3 is a Fit Note, this may not exist, we think the computer system adds this reference automatically. The ESA113 is a request for information made to your GP, your surgery should be able to give you a copy. The report could be your ESA50 although I would expect it to named as such.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems