I have just moved into an elderly but well-built bungalow.

The cement infill at one corner of the roof has brocken away.

As it is easily reachable with a ladder I want to fill it myself.

I would like to use a ready-mixed product.

I am in easy reach of Screwfix and Tool Station.

Is it feasible? If so which product?

TIA

--
Mint 20.04, kernel 5.4.0-42-generic, Cinnamon 4.6.7
running on an AMD Phenom II X4 Black edition processor with 8GB of DRAM.