As this is a new home the first thing I would do is get Bovis to send out an electrician to check that it has been wired in correctly This is a fairly simple timer to connect and with it being new my first thoughts are either incorrectly installed or faulty timer.
Good morning Sarah,
If you are a new home owner with Bovis your heating system will be covered under the 2 year build warrenty as required by NHBC.
Modern builds have multiple zones (eg upstairs and downstairs heating), have you check if you have set the timers for both\all zones?
Secondly, its worth setting the timer to the manual off position and checking the boiler doesnt come on, this proves its receiving instructions from the timer.
Next you want to set the timer to manual on and check when the on light shows on the timer the boiler starts to come into action within a minute or so.
Please let me know how you get on with these diagnostics, but rest assured the Bovis team will be able to assist you for any fault.