You will need to get your soil into the right condition to recieve the seeds or plants , you want to grow. The smaller the seed the finer the soil should be, plants ... cabbages and onions like firm soil, levelled and firmed with feet or roller.
You could try using a hand pronged cultivator, it will break up soil into smaller pieces ,then rake to level the area, then make drills with a hoe and sow seeds.You need to look at a book to get the spacings between rows and plants for each variety of veg.
AS your soil is clay at one end,I would recommend mulching this with plastic,compost or manure ,the winds will dry out the big lumps of soil into the equivalent of house bricks which are very hard to break into small particles once dried out.
Good luck .