Only problem I've come across is when connected to LAN2, I've no internet connection? Do I need to set this up somewhere?
I'm not entirely sure what you mean? Could you describe your set-up a bit more, with specific reference to which ports on which device are connected, and their respective IP addresses.
[Edit], if you meant that when you connect the router to Lan2 instead of Lan1,
it doesn't work, this is as intended. Connect the router to Lan1 as it is
the only port bound to the PTM WAN connection (VDSL2) in the router by default. Lan2 is to allow you to connect to the router itself to collect the stats.
BTW, it's also occurred to me that
perhaps the settings you are seeing (i.e. the values of Interleaving, INP and delay) have been set by TT in order to
ensure the line is capable of withstanding noise without it affecting your IPTV. In other words they're there to prevent that, not necessarily because it has happened. But I have no idea how TT approach this, or whether these values have changed at all over time for you.