This paper draws on research conducted in four publicly funded secondary schools in the South-East of England that explored the higher education decision-making of prospective first-generation university entrants accessing school-based widening participation interventions. It begins by introducing an "ecology of intersecting influences" approach that opens up the multifactorial and uncertain nature of decision-making. Interviews with staff and focus groups with young people (aged between 13 and 18) highlighted the incremental and inter-dependent nature of higher education decision-making but also the importance of attending more closely to the diversely constituted, non-linear intersections between its situated, structural, material, temporal and relational dimensions. In the English context, these include a highly socially stratified university sector and graduate labour market plus significantly increased personal costs, all of which make it harder to calculate the individual "worth" of a university degree. The paper concludes that when higher education decision-making is conceptualised as both an "ecology of intersecting influences" and an "elastic plane," this better captures how opportunities and constraints differently play out in the decision-making of prospective first-generation entrants over time, avoiding the imposition of normative, homogenising and limiting assumptions about the difference made by different family/social positionings.