https://www.slab.org.uk/faqs/what-do-i-need-to-take-when-i-first-see-a-solicitor/
You must show that you are financially eligible or your solicitor cannot do any work for you. They need to know about your income, savings and children or other people you are supporting. You may also have to give information about a partner if they live with you. You should, for example, take:
You should also take any paperwork that the police, courts or procurator fiscal have given to you.
If you are in custody your legal aid solicitor will tell you what you need to do to show what your financial situation is. We check with the Department for Work and Pensions, banks and employers to make sure the information we get from applicants is accurate.
The information you give must be true and complete – if it is not, we may withdraw any legal aid we grant you, you may have to repay the cost of legal aid you have received for your case and you could face criminal charges if you have misled us or your solicitor.