Hi Peter,
My allotment plot is in New Malden (Kingston upon Thames) and is the same size as yours (although I do have the benefit of an additional half plot under my wife's care).
Have been working this plot for 4 years.
Depending on your needs (how much fruit & veg you need or intend to grow) you may find that your standard plot may be a bit too small to accomodate all the things that you listed (greenhouse, ducks, swale, pond, beehive, fruit trees etc). And by the way, you didn't mention a shed, although you might not need one (I myself haven't got one and have only used a wooden chest to store my tools. Plenty of space saved. The downside is that I have no rainwater collection facilities).
So what I mean is: you may have to prioritise all these elements, as space will be limited.
I found the following plants very rewarding:
- Fruit trees on dwarf stock: I planted these in the middle of the plot so that they form a little "oasis". Plum (Tzar), cherry (you may need 2 or more of these trees if they are not self-fertile and there are none on the neighbouring plots) and apple (again at least 2)
- Strawberries (I have 3 beds as well as some scattered under the trees & bushes)
- A patch of black currants underplanted with strawberries.
- Herbs: I have a mediterranean herb garden in the driest spot of the plot - rosemary, lemon balm, oregano, thyme, hyssop and lavander. Initially also had mints but had to remove them as they were becoming invasive.
- Other great herbs (growing here and there, especially between the trees): perennial chamomile, annual chamomile (this will self-seed every year), borage (another self-seeder), calendula (also self-seeds), bergamot (perennial with beautiful flowers), and lovage (a perennial - it grows very tall, over 2m in my experience, and very wide)
- Plenty of stinging nettle !!! If you have this growing on your plot as a weed, do not destroy it !!! If it grows in an inconvenient spot, try to replant it. I find nettles very useful to cut down and add to
compost heap or liquid fertiliser about twice a year.
- Phacelia can be sown periodically (especially on vacant beds after the autumn harvest). It's great for adding to your compost heap, but it's also great bee fodder when it flowers in summer. And if you let it flower and go to seed, it will keep self-seeding year after year.
- Same for mustard - pretty yellow flowers that attract bees, lots of green matter for mulching / composting
Other plants I grow on my plot:
- A strip of raspberries (mine are summer-fruiting) - so far not very rewarding as fruit yield has been low due probably to exposure to strong winds
- A patch of about 10 or 12 comfrey plants which I use to make liquid fertiliser or mix into the compost
- 3 gooseberry bushes - nice fruit
- I've planted chives in several spots but for now they have been growing very slowly - haven't had much yield from them
- Kept several bushes of brambles that grew as weeds on the edges of my plot - their fruit is excellent
The annual crops that do very well on my plot (probably will on yours as well): potatoes of course (I grow these under sheet muching, no digging required), beans, broad beans, runner beans, squashes, courgettes, beetroot, radishes, and all types of leaf vegetables, especially lettuces
I hope this helps - good luck !
L_