Almost all of the experts disagreed with them so there was no credible thinking behind their campaign. It was based on the rejection of everyone who knows what they're doing. They're hoping the EU will throw them a bone because of the trade deficit (despite that argument being built on sand) but that's really the only policy they have that involves gaining sovereignty and not hurting the economy massively. Even that is dependent on charity from an organisation that Boris compared to Hitler, Gove wanted to end in a "democratic liberation" (iirc) and Farage despises.
His comment about the SNP being prepared sounds about right. They're the only powerful party (i.e. not UKIP) not in turmoil and the only one that got a clear answer that it wanted and they have one of the best politicians in the UK from what I can see.
https://www.theguardian.com/commentisfree/2016/jun/26/eu-referendum-nicola-sturgeon-snp-union