The hay is very good usually - mine love it anyway! Some bales can be dusty though so sometimes I lay a tarp out on the grass and take out a bit of the bale and give it a good shake and leave it out for 20 minutes before bagging it in old Megazorb sacks.
As for price, it is about £6 for a meadow bale which is a little on the expensive side but it lasts my four between a month and two months and is cheaper than pet shops! They also do rye bales. I've only got these once when they were out of meadow hay and they are slightly more and the bales seem slightly smaller. Megazorb is about £7.50. I also get Burns Dandelion and Plantain at about £1.50 each and SS for about £3.50 for a medium bag.
I also know that there is another place in Wilmington (about 5 minutes further into Kent) that I've been told about but I've never actually been there.