Are you just trying to fit rawlplugs or anchors?

If just fitting rawlplugs...
- Go to Ebay and search for "8mm diamond core drill"
- About £8 from Hong Kong (Blue or Orange)
- The thick tab/annular end is sintered diamond

Do not use tile-bits, they are usually thinwall with a diamond coating
not a thick wall of sintered diamonds (100s of holes).

I use them often in 8-20mm for various tasks, domestic & industrial
machining.
The diamond does the work so you can use a small 9.6V right angle
cordless drill in a confined space.