Not particularly. Or yes she is, but not for this reason.
Governments consider thousands of different ideas for solutions and some are more unrealistic than others. Australia also uses this system and has done for 40 years, it just makes for a funnier headline. Joe vs the Volcano comes to mind if you've seen that film.
Why she's scary is because she's an idiot. She is part of a milquetoast barely conservative government that she is pushing to the right, not understanding that beyond the horizon that she is so faithfully galloping the troops towards is an angry mob that will hang her from a lamppost in the middle of Parliament Square for the colour of her skin and national status when she reaches them.
She either doesn't understand that there is a far right element in British politics that is more than happy for her to march her party more in line with their values, or she does understand it and her political career is in fact one extremely long and drawn out suicide attempt.
Not to suggest that anti-immigration is akin to the far right, of course, just that this isn't her only horse in the stable as far as moving to the far right is concerned.