Ask yourself, is my current speed limiting anything I am currently doing online ?
Do you plan to do anything new ?
If it's all working as you need, I would not bother upgrading UNLESS you need to upload big files, normal broadband is limited to 1 Mbps whereas fibre can can be much faster.
What are the estimates for your line on fibre ?
I am on Faster Fibre with the Speed Boost, syncs at 55 down 17 up, throughput around 50/16.
It really is about how you use your broadband as well as all out figures. We are a media-hungry family, with lots of streamed media on the go on multiple devices as well as almost constant gaming from teenagers, our service rarely skips a beat.
Get them to tell you what speed to expect. I am on what is advertised as an average of 38mb but get 20mb. There is a cabinet 23 paces from my front door but the one my phone line is connected to is a quarter of a mile away which is a lot of copper between me and the cabinet. Unless they run a new cable all the providers use the same Openreach cables, and will give the same speed unless you pay extra for speed "boosts".