Just listening to music on Bose speaker from phone. Every time the boiler fires up, the music stops for a number of seconds then comes back on again. This didn't seem to affect WiFi on tablet or other devices.
It would seem to be a fault with the boilers electrics. I should get this seen to ASAP, as the problem may be more than it seems on the surface particularly if it has just started to happen.
whilst that is sound advise, it may not be the actual boiler causing the issue, but the roomstat (assuming it's RF or WIFI controller). the roomstat would send a signal to the control control via RF or WIFI to start the boiler, and thus may be the trigger for the virgin WIFI dropping.
The boiler will have its own internal thermostat. If that is arcing it will create a pulse of interference. You'll hear this on an AM radio too. The thermostat should have a capacitor fitted to reduce this interference.