Pure geography. Luther and most Lutheran activists were operating in eastern Germany. Rather distant to reach.
Zwingli/Calvin were in Switzerland, and their influence went up the Rhine into France and Holland. Lots of English & Scottish exiles ended up in Holland and Switzerland, and got inculcated there rather than in Germany.
Scottish avenue is via George Wishart, a schoolmaster in Montrose. Just a typical egghead Humanist, who dabbled in the Greek Bible. Once he was suspected of Protestant sympathies, Wishart fled to France and then Switzerland in 1538 and became thoroughly Swissified. Returned as a Calvinist preacher, and took young John Knox under his wing. Rest is history.
It is a mistake to think of English monarchs as "Lutheran". They were "Henrican" (whatever that means). Very ideologically uncommitted. So anybody could pop in and fill the English ideological void with something more substantial. Anglicanism had no body of texts. There's no such thing as "Anglican theological writings" to refer to for reference, explanation or guidance. The first reference piece was the Thirty-Nine Articles, but it was late and brief, with barely any commentaries. By contrast, Luther and Calvin wrote tons, and in great depth. England inevitably had to import.
The "Lutheran" element in England was very minimal - there was an early small group Cambridge eggheads who read Luther for kicks and there was Archbishop Cramer (who had served as an emissary in the German court). But that's about it. Most of the rest of the English reformers (like the Scottish reformers) served long sojourns of exile in Switzerland/Strasbourg/Netherlands, and came back deeply indoctrinated as "Reformed". English Puritanism has a lot more in common with Calvinism than Lutheranism.
