Business Casual are means to wear smart clothes that are also comfortable. It is professional and appropriate for the environment and does not limit employees to wearing suits, ties and blazers.

Indeed have a handy guide on ‘Business Casual’ click here for more information –

https://uk.indeed.com/career-advice/starting-new-job/business-casual

When you start a job, you will be asked if you have the right to work in the UK. There are a number of documents that you can use to prove this but the most common is a passport. The employer will want to take copies of the document and will make checks to ensure they match your true likeness.
There are a variety of other documents that can be provided – the .Gov website provides a list of acceptable documentation. You can view this by clicking the following link – https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/998170/6.7578_-_HO_-_PBS_Employers_Right_To_Work_Assets_V3.pdf

A P45 is provided by a previous employer to show how much your payroll and tax information. It is not uncommon to find yourself in a situation where you do not have a P45 – especially if it is your first job.
If you don’t have a P45, you can fill in a New Starter Checklist which will allow your employer to add you to the payroll system and tax you correctly.
You can see this form by clicking the following link – https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/963434/Starter-checklist_English_2021_2022.pdf

A probationary period is a effectively an employment trial. During this period, the employee and the employer can call an end to the relationship with minimal notice if they do not feel it is working for them.