Any descent HSS drill will do considering the small amount of material you will be removing, but you do need to give the cutting edges 0 degree rake by grinding the faces of the lips this will reduce the amount of snatch you will get when drilling through. It would be best if you could clamp a piece of scrap plate behind where you are drilling through, this will help.
P.S. don't buy something cheap from B&Q get a Dormer drill
Last edited by bilibib; 03/06/20 12:59 PM.
