Sandman,
I chased speaker wire into the walls in my house last year. It is also plaster on brick. I just marked 2 lines about 10mm apart. I then chain drilled down to around 8-10mm deep using the depth gauge on the drill, finished of with a chisel and hammer. Didn't take too long at all. Finished with PolyFilla and then painted.
Do not use an angle grinder, you'll be cleaning the whole house for months afterwards!
Lee.