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A high-efficiency spin-photon interface is an essential piece of quantum hardware necessary for various quantum technologies. Self-assembled InGaAs quantum dots have excellent optical properties, if embedded into an optical micro-cavity they can show near-deterministic spin-photon entanglement and spin readout, but an external magnetic field is required to address the individual spin states, which usually is done using a superconducting magnet. Here, we show a compact cryogenically compatible SmCo magnet design that delivers 475 mT in-plane Voigt geometry magnetic field at 5 K, which is suitable to lift the energy degeneracy of the electron spin states and trion transitions of a single InGaAs quantum dot. This quantum dot is embedded in a birefringent high-finesse optical micro-cavity which enables efficient collection of single photons emitted by the quantum dot. We demonstrate spin-state manipulation by addressing the trion transitions with a single and two laser fields. The experimental data agrees well to our model which covers single- and two-laser cross-polarized resonance fluorescence, Purcell enhancement in a birefringent cavity, and variation of the laser powers., Comment: 7 pages, 5 figures. Supp. info: 7 pages, 9 figures