This is my first attempt to answer a question here, so please bare with me.

England was one of the first European kingdoms to expel their Jewish population. The did so under King Edward I in 1290. Up until that time Jews were direct subjects of the king, and exploited via a special exchequer. The Edict of Expulsion wasn't revoked until Cromwell.

The expulsions continued. France in 1392. Spain in 1492. Portugal in 1497.

Germany was different because it wasn't a unified kingdom. Yes, some German principalities and kingdoms expelled their Jewish population, such as Bavaria, but Jews couldn't be uniformly expelled. And they were often tolerated by nearby jurisdictions.

Poland is a good example. Fleeing from German persecution, Jews were granted generous charters by the Polish monarchy. It wouldn't last long. Poland wouldn't last long.

Eventually Poland was partitioned between Austria, Prussia and Russia. Austria tolerated their Jewish population. Prussia expelled them. And Russia limited their freedom of movement, requiring Jews to live in either former Polish territory or the Pale of Settlement.

Source: most of this is from a few pages in The Making of the Atomic Bomb, discussing the backgrounds of the Hungarian physicists working on the project.

For this question, it's worth looking at how large numbers of Jews ended up in Germany and Poland, and contrasting that with how Jews ended up in the UK.

During the early Middle Ages, Jewish communities in the Mediterranean area gradually migrated north to Central Europe. During the course of the Middle Ages, a significant chunk of this population migrated East, to modern-day Poland, Belarus, Lithuania, and Ukraine. Eventually this population expanded until they were a substantial minority in the region, until most of them were killed in the Holocaust. This population grew much faster than the Jewish community in Germany, and even formed local majorities in some areas of Eastern Europe.

England had a small population of Jews who migrated in with the Normans, but after a series of persecutions they were expelled in 1290. Jews were not formally allowed in England for hundreds of years after, until a small number of refugees from the Spanish Expulsion arrived. In the 17th and 18th centuries the legal restrictions on Jews were gradually relaxed. Jews immigrated, but gradually, though the population increased substantially when Jews from Eastern Europe moved in, in the same migration that put much larger numbers of Eastern European Jews in America.

This means that Central and Eastern Europe had a large founding population in the Middle Ages, which had centuries to grow by the 20th century. The UK had a much smaller founding population, which hadn't been there for long enough to expand all that much.