I would suggest you first make a compost heap, which takes a few weeks in itself to provide you with nice fertiliser. So maybe you won't get a big crop out this year due to the shortage of time, but nothing stops you from primeing yourself for a bumper crop next year.
For beds, try the double digging method. you dig a one spade deep and wide trench, and put all the ground you remove in a wheel barrow. Now take a fork and loosen the soil in the bottom of your trench. Now start the second trench right next to where the first is, so you are in effect doubling the first, except you will be putting the ground you dig out of ther second row straight ontop of where the first row was, so the first row wil actauly stand somewhat proud of the ground, and the second row will now be one spade deep. continue row by row filling the last row with the soil in your wheelbarrow.
NEVER step on the beds once they are double dug, as this wil compress them and remove the air spaces etc. you just spend and hour working on. use a large board to stand on and spread your weight if needed.
Apply a layer of compost on the soil before you start digging.... happy harvest.