Do I send originals of school reports with my forms, or will photocopies suffice?
You should send photocopies. Take the originals to the hearing with you in case they are needed for any odd reason.
We have DS’s end of year 5 school report, which was very positive and which we shall include in our appeals paperwork. Is there a compelling case to include Year 4 report (also positive), or is this just overloading the panel with old information?
The more the merrier if it is positive! It shows consistent performance. I wouldn't go back beyond Year 3 reports though. KS1 SATs results are also helpful if you have them and they are good.
We do not have any official school paperwork with regards to test scores in year 5 (we were shown them at the parents’ evening). Hopefully, the head teacher will write these in the form she fills. If the HT does this, will this be sufficient? If not, do schools provide some sort of official paperwork with regards to such tests?
Provided the Head puts them on the form, that will be sufficient.