Thanks for the replies everyone. I've just reconnected to the router over wireless and without any intervention I'm now getting over 100mb which is great.
The only thing of note is that I got a text from virgin today while I was at work telling me they have sent the signal to activate my BB (The one I requested last night) so I don't know if there was just some sort of hiccup with the provisioning system or the SMS notification system, it may even be unrelated.
I've now reconnected my whole network and on my wired machine I am getting this....
So it all looks good. My only worry is my power levels still seem the same to me (Screenshot attached). Now I know the old adage of "if it isn't broke, don't fix it" probably applies here but I'm just wondering if I may experience problems with levels like this (perhapps at peak times?) and should I maybe still buy the FPA?