To go from Liège to Ploemeur, you can book a train from Liège Guillemin (Belgium) to Lorient (via sometimes Bruxelles and always via Paris Nord).
The travel will take between 6 and 8 hours, there are possible trains from ~7AM to ~11 AM.
The two trains with less connections (only one in Paris : Thalys then TGV) would be at 07h52 and 09h49.
To go from Lorient to the Residence Loisirs of Larmor Plage, you can either take the bus (lines 51 or 32) or a taxi.
There will be 3/4 cars rented in Lorient, driven by ESRs for the week. The drivers are asked to retrieve a car when they arrived at Lorient at Europcar.
Location of the Europcar Lorient, near the train station in Lorient (5minutes by foot):
The workshop will take place at different sites in Ploemeur, Kermadoye and Guidel.
Traveling during the workshop:
You will have the rented cars.