Ukip arent really agianst immigration as such, as I understand it. Just the EU freedom of Labour. You have to bear in mind that the UKIP leadership are ultra free marketeers that dont like giving workers rights or protection, something which the EU certainly does. They are seemingly pro commonwealth because they can get cheap labour from African countries who are unprotected in terms of pay and working conditions from the EU (They alos speak English and will bolster up the number of Ultra christian votes in regards to their commitment to scrap gay marriage etc which will not be popular with these people. It is these African commonwealthers which is the only reason why Church membership hasnt quite fallen as much as it should have).
The ironic thing is that their core voter base would defect en masse if they realized this!