You will not be liable for any tax owing up to and including the date of the bankruptcy. By doing the returns you will at least be able to define exactly how much is owing, but this will be established in due course anyway as the Insolvency Service will write to HMRC for these figures.
Bankruptcy UK has been helping the British public with bankruptcy since 1998 and will guide you through the process step by step. We will avoid jargon and confirm all discussions by email within 30 minutes. Call us for a chat about your circumstances on 01425 600129.