If TCX were 'approx 100 Pilots' over subscribed they wouldn't waste the time or cost interviewing Pilots for 'potential positions,' as it is unlikely they will get close to that figure with a voluntary scheme. The e-mail that went out to those invited to interview said the company are 'slightly' over crewed for the summer and this was for a pool of suitable candidates. It also said they are not sure about what they can offer, permenant/part time, which I believe as Honiley says it all depends on interest in the voluntary severance.
There is little fat in the system with other group Airlines during the winter, apart from the Scandanavian part as they do more long haul during that period. They will probably look for contracts to utilise Pilots in the winter, like the skyservice one. But these always attract great numbers on a voluntary basis