The UK does have net neutrality, and it's quite strictly regulated by Ofcom, which produces an annual report showing compliance and highlighting any issues it has investigated:
https://www.ofcom.org.uk/internet-based-services/network-neu...
Things like restrictions on tethering and using a SIM in a router are forbidden.
Unlike most countries, net neutrality has never been a political football in the UK.
Ofcom groups zero rating schemes into three types:
Type one - government and NGO services (always allowed).
Type two - where categories of service (e.g. video or music streaming apps) are zero rated, but any service fitting into the category can apply to be zero rated by the network.
Type three - any other kind of zero rating.
Things like the VOXI Unlimited Social Media packages fit into Type Two, so are expressly permitted.
For the rest, Ofcom assessed the impact on consumers, which is generally low.
This is not net neutrality, all network traffic is not treated equally.
Ofcom seems to have invented their own definition of net neutrality and placed it on that website, but calling a tail a leg doesn't make it a leg. This is tiered access.
It doesn't meet a perfect theoretical definition of net neutrality, but it's a set of defined legal limits on the extent to which providers can treat different kinds of traffic differently.
Net neutrality is not theoretical, it is literally the default setting.
Any deviation from that default requires special effort be taken to identify network traffic and treat it differently, and as soon as you have made that effort you cannot truthfully claim to have net neutrality. The UK does not prohibit net neutrality but it does not require it either (according to the comment I replied to which I have not verified).
Ok but the main limit people care about is music and video streaming being treated differently
What would be the model of a country with stronger net neutrality laws? I think EU regulations are now a touch stronger than UK regulations due to post-Brexit divergence, but by world standards, the UK has strong net neutrality protections.