I can't work out if the proposed new law only applies to state officials and organizations or if it applies to religions as well. I think it's the former but at the very least the courts would be influenced by this legislation when considering accusations that religious practices covered up abuse.
I assume the law won't be retrospective, so the WT has time to get its house in order, but whether they will or not is another matter. If you create a culture where all external criticism is claimed to be lies then why should you change?
All I can say is that in the future any elder in the UK who receives a report of alleged child abuse would be crazy not to go immediately to the police.