See the Prices page but in a nutshell:
£100 to join Gigaclear
£0 or £95 to connect the fibre between your house and the ‘pot’ on your border depending on whether you DIY or use Gigaclear’s contractors (1/3rd of Gigaclear’s current customers went down the DIY route)
£37 per month for the entry level 50 Mbs symetric service
So £100 to £195 up front and then £37 per month ongoing.
However, that’s only part of the story. Please see the Prices page for the full information.