How do I set the Prefix Delegation to /56
No idea, you need to ask on a TP Link forum
What options for Internet Connection Type do you have?
I've always Native on my Asus and that worked with BT.
On every TP-Link device I've seen (I seen quite a few), they pick up the /56 delegation from WAN DHCP. I wouldn't trust online IPv6 Checkers, one that appears at the top of my searches says my IPv6 is not functional, while others say it's fully functional.
IPvFoo is a great little extension
To check if your devices think they are using IPv6, I'd be checking in their device settings. On an Android 15/16 phone this may be Settings>About Phone>Detailed Info & Specs>Status>IP address section.
What options for Internet Connection Type do you have?
I am not sure I followed advice on here ages ago to set this up. My son's pc cannot pick up ipv6 so unsure if the online IPTV test is wrong. I messaged BT and they give me info on settings so I will try it when noone is using the WiFi. One thing I noticed is my password on ipv4 seems to have more than just BT added so I am unsure if that would be an issue too but I cannot change it right now as internet is being used.
The username is correct. It has no bearing on your IPv6 problem.
Just looking at your original screenshot again, you appear to have IPv6 connectivity.
I changed some settings and now have this. Is ipv6 better than ipv4 or does it really not matter was just assuming if it was available consoles pc etc would connect to the better one but they are always on ipv4
No, IPv6 isn't 'better' than IPv4. IPv6 was introduced because the world has run out of IPv4 addresses.
There are very few IPv6 only sites at the moment so it isn't a problem if you don't have.
I did that for a long time - no BTHub, but then DV came along so I had to yield to a SH2.