Hi John
Welcome to the forum.
You might want to have a look at the following FAQ which explains where everything is;
www.benefitsandwork.co.uk/guides-for-claimants/faq/forum.
Yes they always say that and I always ignore what they say, if you have a good supporting letter from your Doctor, then send it but keep the original.
I have seen some Doctors that are not fit for purpose, one paragraph and claimants have paid for them, so check any supporting documents before sending them.
Gary