Instead of just going away and leaving this thread dangling here's a follow up...
Decided to bite the bullet and order the VR2800 for £150, plugged it all in - found the phone lead (RJ11) was somewhat on the short side, as is the mains adaptor lead (12v) so its sat on the window ledge in the same place as the billion 8800nl r2 was - which in turn should show real like-for like performance.
I'm on plusnets VDSL 40/10 product ( minimum term on this expires in september - so the next quest is to find out who charges what and then haggle plusnet to match the cheapest /come up with something competitive again)
pugged it all in - set up was simple it was just a case of entering username@plusdsl.net and the account password and that was it, then changing the wifi ssid + password to match that of the billion ( which in turn matched that of a much older router) to avoid the hassle of having to change every wifi device and of it went.
My wifi repeater can now be retired as the wifi extends all over the property - including outside previously i was plugging a repeater in or using a phone hotspot to get wifi outside, without the repeater the billion was poor, with it the poor wifi just stretched a little further
Billion router whilst at bottom of garden speeds about 0.1, Tp link speeds at 32mbps
Second bonus, i've got a few smart plugs ( glorified timer switches that can be controlled over the internet) i had these down as broken as they kept randomly turning off for a few seconds when they were supposed to be on, and on for a second at random when they were supposed to be off - connected to wifi on the new router they have been flawless
Wake on lan is up and running and was relatively simple to set up - the tp link router has a search function in the GUI which makes it easy to find where they have hidden the settings you need, unlike the billion which at times could feel like finding a needle in a haystack
Size wise, the thing is somewhat larger than the billion, although it just fits ( with a slight overhang) on the window ledge