Planting autumn brassicas

Hello,

I will be planting out cavolo nero, red russian kale, borecole and spring green cabbages in September. This will be my second attempt at winter crops. I did them in my first year at the allotment, 4 years ago, just bunging them into the beds we had just made, and things didn't go very well, unsurprisingly.  So how do I do it right this time?  I have clay soil, and the beds that they will go in had potatoes and garlic this year.  I should add lime? I would need to buy some. How much? Anything else?  I need to protect them somehow? I do have some fleece but I'm not really that sure how to use it.  I put netting over them last time but they grew though it, plus I managed to stab my arm on a cane used to hold it up and ended up at A and E for a tetanus shot! 

Sorry if these are stupid questions. I have learned a lot but I'm still a beginner as I have very little time for it, and my practical building-stuff skills are absolutely minimal (with a lovely scar to prove it).  I have learned to put bottles on canes, at least!   

Oh and for my other beds, what shall I do? Last year I chucked fresh-ish horse manure on top in October, but in March I just had to rake off all the unrotted straw. Is that supposed to happen? I've had more manure in a compost bin for a year or so and it is still full of straw.

Thanks. We don't have a bird problem, due to the fox problem! I have a lot of chicken manure as I keep hens at home, but I can't use it anywhere that I don't want dug into. I tried dried blood in my first year, which was a big mistake.