You can submit further evidence, but do remember that it needs to be evidence as to your care and/or mobility needs at the time of your application, not at the time of your tribunal.
In theory, the DWP should submit all their paperwork to the tribunal, but don't take it for granted - send in all the documents you want to be sure the tribunal sees.
When you've got over the shock of the decision, take time to read our guidance on DLA appeals, which will give you more detailed help.