They don't write prognosis normally, unless terminal and getting life insurance out early.
I was given copies of my pathology though to claim against my trauma component of my life insurance at my request. My breast surgeon did this.
My oncologist did my longer term medical certificates as so ill on chemo.
They actually don't normally give you a treatment plan copy but you should get a side effects sheet for the chemo you are getting. So write it all down what they tell you. It helps.
You can ask for copies of all your test results. Handy to have these to refer to if needed in the future.
Your surgeon should be sending a letter to your GP after consult and surgery. That's normal practise...or at least a copy of the discharge letter should be sent to your GP from the hospital where your surgery was done.