There seems to be a real fad for raised beds at the moment and I see people on our allotment site building beds on perfectly good soil. They then import bags and bags of proprietary compost to fill them!! As Two_Sheds has said in an earlier post, use raised beds only if your soil is so poor that nothing will grow. (I have three raised beds on my plot right at the front where there is mainly rubble.) I would approach your veg plot on the basis of "suck it and see". Take out the big stones (you need some stones to give you drainage and stop the area becoming waterlogged) which could cause a problem with root crops, add plenty of organic material, plant up and see what grows well and what doesn't.

__________________
Gardening is a matter of your enthusiasm holding up until your back gets used to it.