Hammerandtongs- I would recommend you use charcoal, which does take a bit of getting used to, or you could try coal. The problem with the latter is that the only readily available stuff is house coal in bags, which may not be suitable, and seeking the advice of many coal merchants is a bit of a waste of time, as they are mostly not experts on the matter of forgework(!). Having said that, I have used crummy smokeless house-coal to forge and even fireweld, so you never know. An excellent blacksmith's coal still available (I think) is Maltby Bingles from RJB.
I have never heard of a foot-operated blacksmith's bellows (not that I'm an expert), but if it's from one of those farriers forges, or one of those jewellers/apothecary bellows you will definitely have problems using coke.
I can't offer any advice on reconditioning leather, other than that I would carefully consider whether it is worth doing, as leather, unlike wood or metal, can't really be brought back to life once it is knackered, especially for the purpose of rigorous use as per a bellows. Better perhaps to replace it?