HI! In addition to other solutions, I want to share with you two bugs that I discovered on YouTube that can make survival mode even easier, in particular these are infinite throwable objects, such as grenades and flares, and infinite pistol and shotgun ammo.
The first can be used immediately at the beginning of the story while the second requires obtaining the c4 and clearing an area in the basement of Buckingham Palace.
Below are the relevant illustrative videos (they are not made by me, all thanks will go to them and the work they have done).
INFINITE THROWABLES:
UNLIMITTED AMMO: