You pretty much submit the same stuff from the PMV but updated evidences from the time the 300 was granted. Don't worry too much about a lot of evidence... some people apply for the 820/801 from 300 within a couple of months so they don't have much difference in evidence anyway, and it certainly won't be assessed as a straight 820/801 app.
Don't worry about new police checks unless they ask for it.
New Form 888s, new statements (you have to do the online apps again anyway so the boxes are your statements or you can write new ones), relationship evidence and anything new since the 300 grant, marriage certificate, all the IDs again, etc.
Should be pretty easy if you kept all the stuff from the 300.
You need to apply online now. Most people think they need certified copies but you don't. Just upload clear color scans of everything.
Don't worry about new police checks unless they ask for it.
New Form 888s, new statements (you have to do the online apps again anyway so the boxes are your statements or you can write new ones), relationship evidence and anything new since the 300 grant, marriage certificate, all the IDs again, etc.
Should be pretty easy if you kept all the stuff from the 300.
You need to apply online now. Most people think they need certified copies but you don't. Just upload clear color scans of everything.