Thanks for the tips & link
I am two minds on when to attempt this as I will be sending it back to Dell within a week or two for investigation to the buzzing noise I have.
Do I do it first and risk them seeing it has been tampered with or leave it until it comes back, but then they may spot that it has been dropped, therefore say that my buzzing problem has been caused by the drop
I plan on upgrading the memory once my repair has (hopefully) been done, so I may leave it until I get it back from Dell. The other option I thought about was putting a note on it and asking if they would remove the dent for me, but they would probably charge???