UKguy
From a recruiters point of view, please be honest about your reasons for leaving.
As it is on your application it does ask reasons for leaving for each of your jobs.
If your not honest and it comes out later you will most likely chucked off your training course as this isw when your references are all processed.
Again as previous posts have said if you are invited to a assessment day you will probably get asked why yuo left that particular job. Just explain what happened.
I cant say how it will affect your application. It will be looked at on the day, but gross misconduct id looked at seriously.
Dont let this put you off, it is merely friendly points.