Digital proficiency, including coding, is increasingly essential in physics education. However, disparities in coding skills among students are influenced by demographic factors and prior educational exposure. This study examines barriers to pre-university coding exposure for first-year physics students across five UK institutions, proposing a fourth level of the digital divide that emphasizes technical and production knowledge in coding. A survey of 199 first-year physics students reveals significant gender and ethnicity differences in coding experience. Males were more than twice as likely to have prior coding experience than females. Students with no prior coding experience viewed it as more challenging, requiring advanced math and powerful computing resources. Despite these challenges, both groups strongly disagreed that gender affects coding ability. Qualitative data pointed to technical difficulties, a lack of role models, and insufficient pre-university exposure as major obstacles. Black, Asian, and Minority Ethnicity (BAME) students reported less teacher encouragement and faced structural barriers similar to those found in literature. The study identifies a fourth level of the digital divide in coding knowledge, stressing the need for targeted interventions to enhance diversity and inclusivity in physics coding education. Recommendations include improving pre-university coding exposure, using gender-sensitive teaching methods, providing consistent encouragement to students, and deeply integrating coding into physics curricula. These steps are vital for preparing students for the digital demands of their academic and professional futures, ensuring equitable access to essential digital competencies.