No, in the UK it's unambiguously the other way round. The complainant simply has to persuade the court that the statement seriously harmed or is likely to seriously harm their reputation. Truth is a defence but for that defence to prevail the burden of proof is on the defendant to prove that it was true (or to mount an "honest opinion" defence on the basis that both the statement would reasonably be understood as one of opinion rather than fact and that they did honestly hold that opinion)