Take a look at Calis beach area, outside Fethiye. Plenty of English property owners in the area who rent out.
May could be a bit early season for Oludeniz and Hisoranu is like Blackpool (& Marmaris). Great if you want full English and loud music till early hours.
Fethiye is open all year round and along the promenade are some fantastic restaurants as well as bars, cafes etc.
if you want a beach holiday then Oludeniz or Calis are main ones in the area.
Cheap hotel in Oludeniz is the Morina, bit of a walk up from the beach but I can recommend it. If you want a Private Rental in Calis/Fethiye I can point you in the right direction. Calis has a growing Cycling club as well.