I was bored and randomly playing around with VPN's and things you could subscribe to and I noticed that HBO Max currently had an offer for 50% off the annual subscription via Argentina. If you go via the US, it's only around 12% (I think..).
I checked around to see what locations it was available in and since Argentina is a popular location for YouTube premium because of the exchange rate, I decided to take a punt and it worked !.
You have to complete the whole process via VPN as it's not "officially" available in the UK yet, so, using VPN Unlimited, I set it to Argentina and went to HBO Max to sign up.
Click on the button in the top right that should say "Regístrate ahora" (Sign Up)
On the next page, you'll see the sign up options and the yearly option should have the 50% underneath it, so click that and scroll down and choose "Seleccionar Plan" (Select Plan).
Create your account on the next page - I used a spare hotmail account that I had and that worked fine, but I don't know if you can use your own email.
Click "Crear una Cuenta" (Create Account) and you'll be taken to the payment page.
I used a Mastercard but I entered the correct name and the payment details and clicked "iniciar suscripción" (Start Subscription) and it worked.
You have to go to the email you used and verify the email, so I stayed connected to the VPN and did that and I now have full access.
Just a word of warning though - I did try streaming some content with the VPN still set to Argentina dnd it was horrible - almost 480p in resolution. I switched to VPN Unlimited's dedicated "Netflix" server for streaming and that fixed the problem and the quality was perfect.
Getting on to your TV will be down to you, dear reader