The married 30-year-old is awaiting an extradition hearing, while Megan, 15, has been flown home to be reunited with her family in Eastbourne.
Forrest, who was born in Aberdeenshire, absconded with the schoolgirl last month and the pair spent eight days on the run before they were found by police in Bordeaux on Friday.
The teacher's lawyer, Daniel Lalanne, has said he will not fight extradition to the UK, where he faces charges of child abduction.
Mr Lalanne said: "We have discussed how he feels about being taken back to Britain and he will not contest it. This is primarily because going home will take him back closer to the person he loves.
"His only crime is to have fallen in love with a 15-year-old, without any recourse to violence or manipulation. Of course he is devastated and only wants to be reunited with Megan."
Forrest will appear before a court in Bordeaux tomorrow when formal extradition proceedings will be heard.
The teacher has already admitted that he and Megan fled to France.