Yes better chance of staying with BA at LHR if on Eurofleet. You'll be replacing existing crew that have been allowed the transfer to WW (originally you were going to take some of those places).
Eurofleet is a great place to be - great crew, young and old though younger than longhaul; great variety of nightstops all over Europe (some nice 3 day trips to ATH, CPH, FCO, BUD and a new nightstop in OTP (Bucharest). Chance to bid for trips and days off or just do day trips...and chance to move to longhaul in the future. Enjoy.