“Would it help to re-take tests and send in other scores in addition to the first ones? Or is it seen as academically weak to have to retake them?”
Retaking (even the SAT) is generally regarded less favorably by UK universities compared to the general expectation in the US that you’ll have several attempts to get your best score. UK exams are almost always one and done - a few people do retake A levels but that’s rare (and regarded as a failure).