OK so as promised, an update on how things have been working so far. I will also include links to the products used.
As previously mentioned I decided to purchase the Netgear LB2120
(Link). This was mainly due to it having the ability to switch to "bridge", how much of this was needed I don't know as it worked straight out of the box, without changing any settings. Showing 3 bars with the occasional flutter to 4. Connecting to the discs was simple and I was able to get circa 30mbps however this was now across the entire house. Knowing that this was now functioning and had the ability to attach an external aerial I decided to see how things improved. The items I ordered were: Poynting Aerial (
Link) and, as this has SMA connections, I ordered the SMA-TS9 adaptors (
Link). However due to the poor quality of the connectors, they kept falling out of the back of the modem. I therefore ordered a different type of adaptor (
Link). These arrived bright and early yesterday. Within half an hour the aerial was connected and in place. The Netgear now shows a solid 4 bars, but equally important I was now receiving around 50-60 mbps. Running speed tests today I am getting in excess of 60 mbps consistently, topping out at one point at 80 mbps.
These are all based on the download speed, upload has remained fairly stable at around 15 mbps
@Furtim