does the fact that Britain and Japan are islands enable or deterred migration to and from those places? explain

No it does not affect the migration.

Explanation:

The countries of Britain and Japan are two of the most wealthiest island nations of the world. The islands even though do not have much land route for going to other countries but still it did not affect these countries of the world.

People in huge number migrated to these two nations because of the availability of jobs and employment opportunities in these countries. More over the living standards were also high in this country which attracted a lot of people.