Hi,
I got my allotment last year about this time and it was a totally new plot covered in weeds.
In the spring the weeds will shoot up in a most demoralising manner. I tried splitting up the work into small sections and tackling it a bit at a time, that definitely helps the mental battle.
Clearing a section then planting it helped keep me cheerful and made me feel like I was making progress. At this time of year, you can clear a section and put in garlic (as long as it isn't too frosty).
I built 2 compost heaps from pallets. As soon as that was done, the plot felt much more like an allotment and it gave the space some structure so it didn't look like a barren wasteland. If I was placing them again though I would probably put them in the middle of the plot rather than at one end.
I also used weed control membrane to try to slow down the weeds. I discovered that the thin membrane is not enough by itself to block out the light, you need to cover it with a mulch to keep out the light. Another plotholder gave me a large sheet of plywood which is very effective at killing off the weeds. Depriving the weeds of light should help with the later sections but it does take time to work, the primary benefit is that it stops the problem getting worse.
I have found that turning over the soil with a fork and removing all the weeds by hand is the only thing that really clears the ground of the difficult weeds.
To help gauge the amount of work you will have, you could see how much you can clear in an hour working at a steady pace. Divide the total area of your plot by the amount you cleared in the hour to get a rough idea of how many hours you will need to put aside to getting things as you would wish it.
Despite being pretty busy elsewhere and pretty lazy at the allotment, I managed to grow all sorts of things in my first year so you should definitely have some encouragement come harvest time.
The only shortcut in the process that I know of is to bribe your friends with beer and/or the promise of some nice veg at some unspecified time in the future. Then get them to do the work for you.
Good luck! Let us know how you get on.