You will be able to use a 9 inch angle grinder with a 230mm blade. I've done lots of them, although I'm a retired bricklayer and can confirm it's very tricky. Go to any hardware store for your masonry blade its cheaper than a diamond tip ($5 to buy one blade, which will do the job). I've never used a concrete saw because they are too heavy and too expensive ($120 a day to hire).
Start by using a plumb level to mark out the area with white chalk. It's not a load bearing wall so you will be ok. Then stand on two woodensaw horses: plank them out with 4 or 5 planks (don't laugh - I always put safety first and never had an accident in 55 years of using the blade). Start by cutting out the perps, not the horizontals; they will come out easier. Then you will be able to take out a couple of bricks from the centre panel to get at it. Once the centre is out, the saw won't cut right through the brick so knock off half the brick then use a lump hammer (ie. mash hammer) with a cold chisel and bolster and an old carpenders saw. Then chisel off the back of the brick - if you are careful enough you can turn the bricks around and still use them after 2 weeks clean down with a 8 to 1 ,8 cups of water 1 cup of spirots of salt 500 ml (from a hardware store).
Use 6 sand to 1 cement to make up some mortar. Mix in a bucket with a couple of inches of water and then add teaspoon of dish washing liquid and stir it up to make the mortar plyable.
Hope this helps.
ps. have an assistant behind you in case the angle grinder kicks - and they will - you must hold it firmly while your offsider can pull the plug ie, pull the socket out. That's how we did it - the best and safe way is to a trady in cheers.