1) Can I still issue manual invoices?

Yes. If a business issues paper invoices it can type the selected data contained in the invoice into functional compatible software this includes spreadsheets. In addition the business can take a photo of the invoice and scan it into their software.

2) Do I need to record every line on the invoice?

No. Where more than one supply is recorded on the invoice and these supplies are within the same VAT period and charged at the same rate of VAT you can record these as a single entry.

3) How do I record petty cash purchases?

Where you are claiming input tax on employee expenses and your employee provides the combined value of more than one purchase, you do not have to record each purchase separately. The business can record the total value and the total value input tax due.