HI COGGY I have used the arnold laver depot in chesterfield,and have aways found what i want,and at reasonable prices. They have a retail shop,but also have a trade department,and you can ask for whatever you want to be cut to whatever size. I am unsure whether they charge for this ,and how much, but it will be worth asking.
I bought a whole fence load of tannalised timber to replace my garden fence. It came freshly treated,and cost less than from the likes of b&q, plus it only cost a few pound to have it delivered to my home some 20 miles away.
So yes,on the whole, i like lavers,and they have had a decent reputation around chesterfield for as long as i can remember.
Try them,and if you dont like what you see,you can always go elsewhere
regards
JOHN