[fletch]

I'd much rather have a clay based soil than sandy, stony or chalk basedas it's full of nutrients, the trick is being able to get plants to access it. Tons of organic matter is the trick.
When I first started on my plot I chucked old growbags, home made compost and all leftover compost from pots etc, forked it in and left it. After 2 years the difference is amazing compared to the beds I haven't got round to yet (I'm working my way through them, only 3 to go now).
When planting/sowing I hoe a drill out or make single holes with a trowel and leave the rest untouched, I don't see the point of digging whole beds over (just attracts more weeds IMO). Then in Autumn I quickly dig the lot over after chucking any old growbags, compost etc. on it again and just leave it.

Agree with Chimaera too, most plants love it and I get really good crops, although it's not very good for carrots (which I do in pots), but I've had decent parsnips from it.

[noshed]

I bash mine roughly with the back of my fork.
And I bung as much compost/manure as I can on in the winter.

[8doubles]

You need some Clod-hoppers, normally 6 year old boys in the care of the parish who follow you around and jump on the lumps in their little hob nailed boots. 

[hunlom]

i can only really speak from my experience,as im a second yr allotment holder. we got ours last june and was a reclaimed field..the council rotavated over, marked out plot said `all yours `... it was a nightmare 1st yr...but after many rotavatings,picking the grass,weed  and any other rubbish up as went along,i managed get it something like clear.

 about november i covered it with 4" of well rotted cow muck/straw and left over winter..
went back up in mid april and started a small patch with rotavator just to see what soil was like...WOW what a diffeence...went over whole 20mx25m patch in 6 hrs...no weeds and a total different soil...finer and more crumbly...a lot easy to work with..still not perfect i grant, but same again next november and who knows.

i know a lot of the more traditional amongst us would prob not agree with with this method. but it worked for me....i now have half covered over with black sheetin to keep `dormant` while on the other i have 6 rows spus,4 rows onoins,4 rows peas.

 hope this may help...im no expert ,but like i say, it worked for me....