I've built an enclosed front porch, about 4m2 including 1m2 of
original porch recessed in front of the old front door.

Before laying some Indian sandstone that I have lying about, on my new
concrete floor, I need to raise the level of said floor by about an
inch and a half. Am I OK just bunging in a very sloppy mix of sharp
sand and cement, then laying the stone once it's set, or should I mix
something stronger?

Cheers
Richard