Carrot soil - lawn dressing mix

Hello,

I'm new here so go easy on me if this is a crazy idea. I've got some raised beds, about 450mm deep. As carrots are apparently bit tricky I've sectioned of an areas for them and I'm going to sieve to soil. Currently, its just this


There seams to be a bit of debate about the importance of sand but in the interest of drainage I was going to add some.

So... I don't have any sand laying around but I do have a load of lawn and turf dressing that i don't really need. It feels like its mainly sand anyway. Would this be a good idea?

I was also going to put 50mm of gravel down in the bottom to help drainage, just to be sure.

Any input welcome