The government has not assessed the changes in the level of homelessness since 2013 in coastal communities. However, the number of households accepted as being homeless and in priority need for all local authorities in England from the financial year 2004–05 can be found in Table 784 here:
The above link provides information on levels of homelessness by local authority, so please refer to the Local Authority of Sefton.
A new case-level homelessness data collection system was introduced in April 2018 and will provide a much richer source of information at the household level, including information on support needs. The latest published information is available here: https://www.gov.uk/government/statistics/statutory-homelessness-in-england-april-to-june-2018.