If the RAF had Bf-109s then their development would have shadowed the REAL development of Spitfires, the range would have been increased. But it would have nowhere near been along the lines to make the Bf-109 an escort fighter.
It's simple, a planes development in wartime follows the needs of the war you're waging. The British needed interceptors at the start, so interceptors they had. When the war dragged on their beloved Spitfire needed extra range - so extra range it got.
Germany began the war with nearby enemies, allowing the air force to follow the ground combat. The fighters could move from airfield to airfield on the advance. This meant the Bf-109s didn't need range. When the Battle of Britain began it was quickly realised the long-range escort fighters (Bf-110s) were poor, and needed their own escort fighters. But by the time the need was realised, it was too late and Germany needed interceptors to hold off the increasing bomber offensive from the RAF and USAAF. So, the Bf-109 never needed an extent in range.
Would it have been different with the Germans in Spitfires and RAF in Bf-109s? No.