In my opinion, if you haven't get someone to machine polish, don't even think of using sandpaper!
Absoultely, I have repaired keyed areas on my own car by using touch up paint, followed by wet sanding then machine polishing with Menz Power Gloss (high cutting strength). I can confirm you won't have a hope in hell of recovering the finish with SRP.
My advice, get your keys, drive to local approved body shop, give him ur keys and walk home.
When it comes to paint best just leaaving it to the pro's.
My opinion anyway
In most circumstances I agree with that, however I took my GTi rear valance to a 'specialist' who wanted £250 to prep and colour code the top half, but wouldn't guarantee the finish. Ended up getting a friend to spray it after I completed the prep work. Then I wet sanded with 3000 grit and machine polished, imo, better than bodyshop could hve done. Since then I have prepped and sprayed the front splitter which also came out great.