I only got my plot about a month ago and still clearing it. I have started building raised beds to the right of the plot and could not decide how i wanted it.
I used this free program when planing my small back garden and thought i would see what it was like for the allotment.
I drew it on paper first to plan, 1cm = 1m, Plot size 14.5m x 10m, then simply drew it on Sketchup(free and run by google)
http://www.google.com/sketchup/index.html it took about an hour because i forgot how to use it.
You can shade, add texture and loads of other stuff.
This is my first attempt without adding and texture.
top left is the compost area and top right is the shed(only allowed 6x4) and patio. The two triangles are going to be for my boys(11 & 8yrs) to grow and have competitions against each other. The front and sides will have wire strung across for fruit trees/bushes and the back will have a small fence to stop people cutting accross to get to the sloe/ blackberry bushes.
I am going to try a few different layouts to see what i prefer, then print out 3 lots and write on it what veg i'm going to have for crop rotation.
Neil