The growth of UKIP ,is in response to the two main parties the tory party (conservatives ) and labour (socialist) fighting over a small bit of ground in terms of policy, both have moved their ideology into the middle ground,. Which has meant that many people feel they are not represented anymore by the politicians in this country, so they look for an alternative.
I would argue that before Farage took over UKIP was very similar to the tea party, being extremely libertarian on economic policy and very right wing on immigration and law and order for instance. Farage however realised that the goings were small in terms of voters he could attract and that the goings were good in traditional labour party voters ,who feel they cannot vote BNP (british nationalist party) because it is openly racist, anti semetic and has extremely unpleasant looking and acting people who run it. Farage also looked back through political history and saw how enoch powell a right wing conservative attracted voters from across the political spectrum despite his background. Powell at one point had 80 percent approval ratings by british people for his policies, and could have become Prime minister if a few political events had happened different.
http://en.wikipedia.org/wiki/Enoch_Powell
Powell ,leaving aside his at that time 'unfashionable views' about immigration was pro russia , anti america, against nuclear weapons and believed Britain should get rid of them, believed in an isolationist foreign policy he believed Britain should distance itself from the US, and instead forge a close alliance with russia against the emerging EU power block. Similar in some ways to Ron Paul. Powells weakness and one farage is probably aware of ,was he was guilty of being 'too clever by half'. He was argubly the most intelligent man to ever enter british politics and due to this people would mis interpret his speeches and writings, he was no racist, but being a typical academic he had not enough personal awareness of how his comments might be interpreted by not just the left,but also actual racists who would try to ally with him for their own ends.
Farage is obviously trying to emulate powell's success he even admits he is an admirer , enoch powell is the only british nationalist who ever came near to being PM, the others are jokes or unserious. However Farage is a mere showman and not fit to shine Powells boots , I don't believe he is a racist, or other senior UKIP members, but they are typical politicians, they try and show themselves as men and women of the people when they are not, and they are just like the tory party due to the UKIP threat and to a lesser extent labour trying to attract votes from frustrated british people who have become much more intolerant due to mistakes made by the past labour government ,as they opened the borders for years and let in huge numbers of people from eastern europe. So all parties are creating a caustic nasty environment for their own ends.
Powell was the only British politician to stand up in the house of commons and condemn the slaughter of indian prisoners by british colonial troops (back when Britains occupied india) and demanded the british soliders that did it, be held to account. He was a man of honour, and a rare breed even back then for a politician. I as a british nationalist would vote for such a man.
So UKIP if you notice under farage, has actually moved to the left on certain areas of politics, I won't say policies as they don't have them yet, but farage is after labour voters, so especially in the north of england he is condemning tory welfare cuts,talking positively about the National Health service and speaking about british jobs for british workers, and being more socially conservative, as the old labour party was, the new labour party isn't.
So in it's current form UKIP has little in common with the US tea party, apart from rhetoric about being 'anti establishment' and ranting about the media and political elite,in terms of ideology no.I think, UKIP is nearer these days to the french front nationale, minus anti semitism, thats one thing UKIP cannot be accused of ,many of the biggest donors are jewish.