Right an update on this...finally...

I got a 3B HG612 pretty cheap (brand new) and hooked it up to my old Billion 7800N as a test, no stability issues at all with the line with that. That was after my father FINALLY getting annoyed enough with the BT Smart Hub to want to do something about it. Which was rebooting daily and sometimes when it rebooted itself it rebooted itself a couple more times before it decided it was stable, truly awful.
So I've picked up a TP-Link VR900 v1 - Why not get the better RT-AC68U? Because I wanted something with a DSL modem in as a backup in case the Huawei and this was the only affordable and viable solution.
Why do I say the AC68U is better?
Well for starters the VR900 runs rather warm.
It's got 1 less ethernet port when using it in WIreless Router mode due to the need for port 4 for the connection to the modem (although I suppose the DSL-AC68U has that issue, too).
The setup had me scratching my head as to why it wasnt connection, then i realised the initial setup is strictly Modem Router mode and you need to change the operating mode AFTER setup to get it working with ethernet 4 as WAN.
The firmware is just lacking compared to Asus. You can't change the names of connected devices (when you have 8 android devices connecting things can get confusing), there's no firewall log, the system log is poor at best, it doesnt show system or connection uptime so you have to try and guess if it's dropped from the router log.
I think the wifi range is better on Asus models to be honest.
Considering it's £100-120 which can rival the asus devices depending on sales/current pricing you'd expect more but hey ho...hopefully it will last a long time and the heat won't be an issue.
(I chose the v1 over the v2 because i couldnt find any info at all on the v2, reviews etc, and a standing up router is actually preferred for where it is so...)
Currently Plusnet "80/20" FTTC