If you still need to get to Lorient, the Eurostar and TGV could be your best bet. Journey takes seven - eight hours, five or six times a day, from London via Paris (more like seven hours from November when the Eurostar goes full pelt from St. Pancras to the Chunnel). Fares from £49.50 each way in standard class, around £100 in leisure select (restricted business class) and around £200 for flexible business class; less for youths, seniors etc.
Hmmm, Eurostar is a option. My other alternative is there is daily FR service to Brest ex LTN (sounds alright!!) which is sort of in the same area where I want to go. Cheap enough, me and my daughter £120.00 return inc. taxes.
What Goes Up Must Come Down, Hopefully In One Piece!