Seat upholstery

Depends what kind of use you plan Rod. I've had real leather bike seats in the past. If the bke's used all Winter in rain & snow n stuff, the leather eventually goes white & furry. If it gets left out all Summer in hot sunshine it can go rock hard or crack. Using a good saddle soap, (used for protecting horse sadlles), should keep it in good condition.
Vinyl's usually much cheaper, easier to get hold of & these days, often hard to tell from real leather. It also comes in a variety of patterns. I had the seat on my last trike recoverd several times. The last cover was made up by a local guy in Basingstoke, Hants, using inserts in dimpled vinyl, (like the surface of a golf ball). There's a few names in the Links for commercial purposes section of the forum. Always happy to add more if you have anyone you'd recommend.