Acculturation occurs where culturally different groups of individuals come into contact with each other, leading to cultural changes to either or both groups. For immigrants, home language maintenance is one aspect of acculturation. Studies have shown that home language maintenance is beneficial for immigrant children’s development in various ways. This mixed methods research looked at Hong Kong immigrants in the United Kingdom under the new British National (Overseas) Visa policy. It explored parents’ attitudes towards their children’s learning and maintenance of Cantonese and Traditional Chinese (the home language of local Hongkongers), the obstacles encountered and support needed for supporting their children’s home language development. Age-group-specific differences in findings were investigated. An online survey was used to collect responses from 96 parents regarding 146 children in three age groups: n = 28 in preschool, n = 73 in primary, and n = 45 in secondary. Results showed that almost 90% of respondents viewed Cantonese and Traditional Chinese development as important for their children, with the strongest reason being ethnic identity maintenance as a Hongkonger. More books and community gatherings were found to be needed for creating a contextualised home language environment for the children. Parents with preschool children were found to express significantly higher needs for multilingual development events than those with children in primary. The study suggested support measures and prompted future policies to consider age-group differences in home language learning support needs.