I upgraded to the fibre option when it became available in my area about a month ago.  I found that the wireless speeds were more than acceptable (37mbs download, 7mbs upload) in the room in which the router was located and those adjacent but elsewhere in the house, including my study, it was naff (maybe 10mbs download on a good day).  On the advice of a PlusNet chap (whose name, I am ashamed to say, I have forgotten)  I invested in a pair BT Powerline adapters, less than twenty quid on Amazon and very easy to install (just plug them in),  and bingo, problem resolved.  In the places where it really matters to me I have a rock-solid 35mbs+ download and between 5.5 and 7.6mbs upload.
The Technicolor router may not be the best, but I can't blame PlusNet for the location of load bearing walls in my house hammering the efficacy of the wireless connections but the BT Powerline adapters are a spiffing solution.
I remain a very satisfied PlusNet customer, well Force9 customer actually. I was with Force9 before PlusNet took them over and have never had need to think of changing; from dial-up, through ISDN, ADSL and now fibre to cabinet they have always provided me with a solid reliable service.