Our Boots orders it in in 140g and 280g tubs - they should be able to do it through the pharmacy ordering system in the dispensary (all Boots stores use the same ordering system so if our store can get it, then any other store should be able to as well as long as it's in stock with the manufacturer).
A lot of people use it in a Delia Smith Christmas recipe, so we try to have some in stock around Christmas time. We have had trouble getting hold of it recently though - we couldn't get it at all for Christmas 2008, but last I looked (end of Jan - I'm travelling in the US right now, so not at work), we had about 4 tubs in stock.