In reply to Victoriacake:
As someone that buys a reasonably large quantity of bolts on behalf of a local bolt fund I have become extremely cautions of sourcing bolts or any other hardware such as links and rings. There needs to be some accountability for what I purchase with peoples donations. This advice came from the BMC technical Officer, who has always been a great help.
So gone are the days of getting bolts from fixing merchants and marine chandlers. Its never been easy or cheap to get expansion bolts in the UK for climbing, specifically sold as such and they tend to be a bit on the short side.
I get all the bolting hardware now from Germany and Greece from two companies that make and test their gear "specifically sold for climbing and mountaineering" with many of the items being UIAA and EN:959 or whatever. This I think is the absolute minimum I should do to ensure that bolts the bolt fund are installing are safe to use.
Unfortunately for an individual you will not get a Bolt Fund bulk buy discount and then there is a shipping/customs charge.
Ignoring all this or you don't have a local bolt fund to buy from you may consider "GS Products" a favourite with "seasoned bolters".