Soil underneath patio

Wildlife12

Hello,
I'm hoping someone can nudge me in the right direction, as I'm a bit stumped with this.
I have a very large raised patio, which the previous owner had fitted.
I intend to remove some of the patio slabs, and turn part of it into a raised bed for flowers, shrubs, etc. 
Now, I've lifted a slab to see how it's been fitted, and underneath there's a week cement base, which I've broken through, and underneath that, there seams to be a mixture of sand and soil....more sand really(the rest of the garden is clay soil which I intend to improve by adding well rotted manure,etc).
Now, my first thought to improving the ground (after the paving slabs are removed), is to work in manure, and peat free compost, along with top soil.
Would I be heading along the right lines?, or would adding the top soil be a bit over the top
If anyone can point me in the right direction I'd be grateful.
Many thanks for taking the time to read this.

josusa47

Depends how high you're planning to make your raised beds, and what you want grow in them.  If you make them of, say, two courses of bricks, bigger and more permanent plants would want to get their roots down deeper, in which case it would be worth improving the soil underneath.  If your beds are going to be deeper, or you are only going to grow small or short-lived plants, you could just build them on top of what's there.

Obelixx

I'd be inclined to fill it with half and half well-rotted manure and well-rotted garden compost or spent potting compost or cheap multi-purpose potting compost.  Depends how deep and wide it is and what you're thinking of planting really. 

Wildlife12

Thank you for the replies, much appreciated.