I'm not sure that 'libertarian' is the correct word. UKIP's Douglas Carswell is a libertarian and has published books and pamphlets about his vision for the future.
He is in favour of a free market with little on no state intervention. This includes free movement of labour to serve capitalism. As far as he is concerned, business owners should be able to 'buy' labour at the cheapest cost, which includes immigrants. He looks to Singapore as his model, where over 30% of the workforce is comprised of immigrants.
The above is the main reason that there is conflict between Farage and Carswell.
I also think that there are many facets to being 'right wing'. For example, right wingers can be authoritarian, but not necessarily, and left wing governments can also be authoritarian. What we're seeing in Europe is definitely fuelled by immigration and, unfortunately, this is giving racists a form of cover.