Bus
Buses do stop outside at the front of the station. If you look at the photo on the previous page, there is an exit up a few steps and along on the right, just above the ticket machines. These take you north and may well not be useful (390 to Archway and 91 to Crouch End).
You will probably need to cross the busy main road to catch buses going in the opposite direction, towards central and west London, including 91 (Trafalgar Square), 390 (Oxford Street), 46 and 205 (Paddington), 30 (Marble Arch).
There are multiple bus stops to cope with. Traffic on the Euston Road is slow but the road is tricky to cross. Use only the crossings.
Buses also go along the sides of St Pancras, such as the 24 (Highgate and Westminster).
If you are travelling light, bus may be a good choice.
Also see King’s Cross.