Allotments 4 All

I haven't tried them yet, but they were recommended by Barnowl.
http://www.thecompostcentre.co.uk/products.html

Really good prices for compost, and free delivery! 10 bags minimum, but I guess you can split with fellow allotment holders if you don't need so much?

However, they only deliver in a radius around Woking, as far as I can tell, between Reading and S.W. London:
http://www.thecompostcentre.co.uk/delivery.html

Re-posted from the other thread:

If you're thinking of buying the composted stable manure (Natural Organic Compost) , it might be worth asking for their guarantee that it's free from aminopyralid or other hormone weedkillers.  Bagged products like this have been implicated in 3 aminopyralid contamination cases that I know of.  They need to confirm that they don't spray anything and that the horses were not grazed on sprayed pasture or fed sprayed hay or silage. 

I've emailed the compost centre to ask about the nasties - their email addresses are bouncing my mail, though! I'll try again another day.

... and whatever they say, unless it's *very* convincing, I might just avoid anything with manure in it, and go for the 'growing troughs' (growbags), topsoil, potting compost and other products. (If they are manure free.)

They also sell coal, by the way, including smokeless. (£8.40, 20kg sack.) The 10 bags minimum can be a mix of compost and coal, if you like.