cedar - I totally understand the relief. I think I will feel the same, though I will probably also feel a bit guilty about it. It's strange how it feels 'wrong', isn't it? There are quite ingrained thoughts about food waste in there that I don't really want to explore 
I have to do a seed order because it is a big collective one, and has to be in by 3 October. But it does mean I do get King's Seeds half price, which makes them bargainous! (Definitely recommend joining local allotment associations just for this perk!)
I am really into beetroot now. I never liked it much before, but the ones you grow yourself are so very much nicer than the tasteless and sometimes strangely sweet-and-sour things from the supermarket.
Buddy - welcome to the thread and to the world of allotmenting! It is brilliant. Good time of year to get one, as well, as you have the whole winter to get on top of the landscaping side of things before starting next spring.
For rotavating - there are a number of considerations. First, it depends a bit what weeds you have. It works great on leafy ones, but chop some of the root-generated ones (like bindweed, couch grass, dandelion, creeping buttercup) with it and you will essentially make a million small pieces all of which can produce a new plant!
Secondly - you can do non-dig methods which are just as effective and save the expense of hiring a machine, e.g. covering the ground with weed sheeting. In fact, you will probably want to weed sheet anyway, as it will keep things in stasis for you, and allow you to work on a bit at a time, without having to battle weeds constantly. The cheapest place I found was ebay - you can get a big roll on there that will cover the entire thing.
Thirdly - if you get going now, you have time to dig a couple of beds by hand and plant some green manure over the winter so that you have lovely, rich conditions for starting in next year! You're not too late for over-wintering broad beans and peas either, both of which will fix nitrogen for you in the soil and give you a crop next year! 