Where is the best place to purchase rock salt ??
Your local hardware shop.
Unless, of course, you want it for a whole transport yard; in which case local council?
Depends on how much you want. 25kg bags…local builders merchants. Bulk…Winsford Salt Mine.
Hell, when I was a mere yoof working for Fred Chappell I’ve fetched many a ton out of Winsford. There was an old fella there driving a huge CAT loading shovel, no onboard weighing, but he could put you your exact weigh on…every time. No going back for a bit more or to tip a bit off, The old fella was a class act.
Happy days