But if "free speech is absolute" then it can't be overridden by any other law.
Any absolutist position on any topic is almost certainly wrong. This includes absolutist free speech. The bar in the US is if the speech has some benefit to wider society to allow. And we are very lenient on what we call benefit in these cases. Anyone that tells you the US has absolutely free speech is either lying or just wrong. And in the real world, you can't run society with any absolutist policies including absolutist free speech policies.
That being said, the UK government can pound sand and should be embarrassed by its behavior. UK isn't a serious country anymore. If you want to know why Americans don't really care what others think, this is a really good example as to why. Total clown show...
"Free speech" doesn't mean it can't be challenged.
/not a lawyer