I question the "worth" of tearing up a trading agreement, but be that as it may Farage played very little role in that.
Farage was an embarrassment to the official leave campaign to such an extent that they tried to sue ITV when it allowed Farage to speak on Leave's behalf. According to Leave he either had no impact at all or was an active hindrance. This point of view is somewhat vindicated by his inability to win a seat in parliament either for the Brexit party, or UKIP when he was leader of that party.
After the campaign he claimed all the credit. He's just a typical wideboy chancer that normally would have been limited to scamming the elderly with fraudulent timeshare schemes, but got elevated to a higher station by a freak blast of cosmic luck.