There may be restrictions on the benefits you can apply for based on your status in the UK. For instance, if you come from Europe, you may need to show you have settled status or pre-settled status before you apply. If you are in the UK with a visa or if you have claimed asylum, there may also be restrictions on the benefits you can apply for.
In some cases, British people who have only just returned to the UK may also struggle to claim certain benefits.
It is important to get advice and support if you are being denied benefits due to immigration restrictions.
Some general information for EU and EEA citizens can be found here
Further information for people with visas or asylum seekers can be found here