Your planning, checking, attitude, and decision making in the air seem very good, and your considerations after the flight. In fact I would say beyond the level and skills of most people at that stage. You were definitely right to head back. Unless you have an IMCr, I wouldnt recommend chancing it with a lowering cloud base. You may have landed OK at Lydd, but it might have stopped you getting airborne later and getting back to SouthEnd via an expensive taxi or train ride.