Repairing small area of render on lower part of front wall

[tekman]

Yesterday I noticed that a plant root was pushing out the render on the lower part of our front wall of the house. Upon investigation I found the render to be easy to remove exposing a huge plant root. After a serious struggle removing the root and removing more of the render to access it, I'm obviously left with a patch up job to do on an area about 2 ft wide.
Umm what a dummy I've not done this sort of rendering before and was hoping someone may be kind enough to assist as to what quantities of cement etc I need to patch this up.
The bricks are exposed in this area even part of the dpc. The wall is original to the house around 90 years old and in truth needs to be rebuilt but I just want to patch this section for now.
Had a look through Wickes catalogue and I think the correct cement to use would be their mastercrete one. I would prefer some ready mixed cement to use but go with what I get advised.