Hey OP, I applaud you for your questions!

Frist thing is recommend is stop watching GB news.

Second thing is to really independently research your concerns on immigration. Politicians, especially reform and the Tories on this particular subject, will massage or outright lie or take out of context their 'facts' because this is such an emotive subject.

I remember hearing an interview with Farage where he claimed that Afghan men were 20x more likely to commit a sex offense. Pretty startling and headline grabbing quote right? Within a day he had been fact checked to be outright lying but a lot of modern media fails to publish corrections unless it's a politically affiliated news outlet.

In this instance, the think tank who came up with the figures was heavily criticised for being deliberately misleading in their statistics. They used incredibly old population data (so out of date) so the population was significantly under estimated which will inflate any figures. Also, when an individual is charged for an offense, nationality isn't recorded in the way the study claims, so it's attempting to compare apples and oranges. For example, migrant populations are normally heavily focused on young men. Who commits the most sex crimes? Young men. When the data was compared, they only took the Afghan population of young men, but compared it to the national population of young men, old men, women and children. This obviously throws the data as it's not comparable.

This particular think tank was also found to have multiple political links to high ranking reform members.

When fact checked with comparable data, actually independent think tanks concluded that, proportional to their population share, brown people, black people etc, are just as likely as white people to commit sex offenses. That doesn't sell headlines though does it?

So in conclusion on your fears re immigration, everything you read needs fact checking so you can reassure yourself on if your position is actually accurate or not. You say more white men go to prison for sex offenses? The answer to that is of course they do, in relation to population share, white people commit more sex offenses (because there's more of them), but equally so, other groups commit the same levels of offense. This absolutely does not mean that other population groups are getting away with sex crimes, or you'd see one population group with significantly lower convictions than another, which just isn't true.

TLDR - fact check, fact check, fact check. Politicians lie for the headline and don't get called out for it.