Complex sentence: Financial pressures meant it was necessary to maintain her work as a commercial composer, and her work on the Oramics system covered a far wider range than the Radiophonic Workshop, providing background music for not only radio and television but also theatre and short commercial films.
Split into simpler sentences: Financial pressures meant it was necessary to maintain her work as a commercial composer, and her work on the Oramics system covered a wider range than the Radiophonic Workshop. Using the Oramics system she produced music for not only radio and television but also theatre and short commercial films.