HMRC have issued the guidance What you can do if things are seized by HMRC or Border Force.
This guidance applies if HMRC or Border Force have seized something, such as goods and vehicles, under section 139 of the Customs and Excise Management Act 1979. It does not apply to seizures carried out under any other law.
https://www.gov.uk/guidance/what-you-can-do-if-things-are-seized-by-hmrc-or-border-force