getting to Paris from Calais (via rail)

Hi

I'm looking to get into Paris from Calais on the train, specifically the Calais Tunnel Terminal.

I will be travelling with friends near Le Touquet. They are returning to the UK on the Eurotunnel service (with their car). I want to go as far as Calais and leave them to make my way to Paris.

Is it possible to get a train at the Eurotunnel station? Is that Calais Frethun? Should I reserve ahead or can I get a ticket there and simply get on a train?

My thanks in advance for all help.