New Allotment, New to Allotments

Hi all,
I'll be moving house soon (September), and the garden is big enough and sunny enough for growing.
However, I've never grown anything but a cactus in my room before now, so I've spent the last few days reading as much as I can on the subject.
I think I have a plan of what to do with the garden, the area of which is currently covered in grass.
If anyone could criticise the plan, it would be great:

1. Mow the lawn, remove all weeds.
2. Remove the layer of grass with a spade, and compost this.
3. Double-dig the area set aside from growing (which I understand to mean dig out a trench, aerate the ground underneath, fill the trench with the contents of the next trench dug).
4. Plant mustard and clover on half the area each (ensuring mustard is not on area set aside for brassica and clover is not on area set aside for legumes).
5. Plough green manures into soil, having saved seed, just before seeds spread into soil.
6. Plant 1/4 potatoes, 1/4 brassicas, 1/4 legumes, 1/4 squash and pumpkins with roots like onions and carrots amongst the brassicas.
7. Harvest when appropriate.
8. Plant green manure over each winter and rotate so potatoes follow legumes, legumes follow squashes, squashes follow brassicas and brassicas follow potatoes.

Does this plan make sense, or have I got it completely wrong?
Thanks in advance,
Dan

Sorry, I won't have access to the plot until September, so I'll be leaving everything until next year, with the green manure over this winter. I was pretty sure September/October was too late for much else.
Thanks.

Like your plan! Wish I'd had one similar...! And thanks for clearing up the rotation for me - I've been getting into a muddle with that on my plot! Much easier to understand the way you put it. Good luck with clearing the plot - a lot of hard work, but very cathartic. Dig out all the roots of the perennial weeds that you can find - or they will come back to haunt you forever...!