Remove the turf from your existing lawn and stack the turves upside down somewhere to turn into loam.

Dig the area that was the lawn over and the dig in lots of compost, well rotted manure or any other good humus rich stuff you have, even grass clippings and paper shredding.

It is a little late to start growing veggies this year but I would suggest you plant potatoes, which will help to clean and clear your soil and peas, beans who's roots will leave nitrogen nodules in the soil.

You can try buying and planting out brassica seedlings but unless you've got your bed sorted fairly soon it will be a little late.

Salad crops will still do well, as will kale sown now to crop late autumn/winter good luck and have fun growing your veggies!