There is not a huge selection of direct trains but you can take a train to Montreuil sur Mer where you can arrange a taxi to Sempy.
Arriving by Channel Tunnel or Ferry:
Arriving by car from either Calais docks or off the EuroTunnel it really couldn’t be easier with a relatively quick 45 minute journey.
Choose the old route nationale N1 rather than the autoroute and you will find yourself in la France profonde fairly quickly, with grassy verges and little villages providing ample opportunities to stop for a picnic en route.
It is not recommended that you attempt to holiday here without a car. This is a small village and to fully appreciate the area you really do need a car so that you can explore further a field.
There is ample private and secure car parking at the houses.