BT are now accepting orders for Fibre Broadband from customers served by Amersham Cabinet no.3, the cabinet that serves Coleshill. The service can be ordered from BT Internet and also from a number of other Internet Service Providers. You can see a list of service providers at the following link: http://www.superfast-openreach.co.uk/at-home/buy-it-now.aspx
Note that not everyone in the parish will necessarily be able to receive the fibre service because of line length limitations. You can check availability using this link: https://www.btwholesale.com/includes/adsl/main.html. (The fibre service is labelled "WBC FTTC" in the list of services.)
Happy Surfing!