For a first leather jacket you're not yet committed to, ASOS's genuine leather biker is a surprisingly honest starting point. Real leather rather than PU, decent YKK zips, a biker silhouette that works with jeans and boots, and fully lined so it's comfortable against a thin shirt. It won't develop the kind of patina a quality leather will, but it photographs well, fits most builds reasonably, and costs a fraction of what a proper jacket runs. A rational test before you commit to spending seriously.
AllSaints make the best leather jacket for the money in the UK market — the Cargo has been their bestseller for years because it earns its place. The lamb leather is proper, the cotton lining is comfortable, the YKK zips work every time without catching, and the slim fit is considered rather than fashion-forward. This is the jacket that gets better every year you own it: the leather develops a patina, the shoulders conform to yours, and it starts feeling like it was made for you. Worth every pound.
The original motorcycle jacket, made in New York by the same family since 1928. The Perfecto 618 uses steerhide leather — thicker and tougher than lamb — solid brass hardware rather than zinc alloy, and a belted waist that gives the silhouette its authority. Every jacket is assembled by hand in the USA, the construction is genuinely indestructible, and the design hasn't changed because it hasn't needed to. What every biker jacket is trying to be, done properly at the source.