So allowing 3mm between frames 39mm x 40 frames = 1560mm
Actually, the inter frame spacing is more like 2mm on my Nikon.
And the leader doesn't need to be that long. The Fuji roll I have on my desk has a 40mm leader.
So, I calculate ((36mm + 2mm) x 36) + 40 mm = 1408mm per roll.
The bulk roll you have an eye on is 30.5 m = 30500 mm
30500 mm / 1408 mm = 21.6 rolls.
£81.14 / 21.6 rolls = £3.75 per roll
For that price, you're right to say it isn't much of a deal. But keep the loader. You're bound to find other emulsions at a much lower price. With the demise of Kodak, I think there might be speculation on their films; in particular with the Tri-X which is a bit of a cult emulsion.
Actually, I did bulk load one time. Thing is I found a bulk loader at a garage sale for dirt cheap and there was still some film inside