Here are my thoughts.
1. You will probably have a very difficult time finding a student or part-time employee who is dedicated and will not spend most of their time goofing off while you are not around. These types of employees need a LOT of supervision. That is just a part of human nature. It might be better to subcontract, rather than hiring employees.
2. In the USA, we have office parks where you can rent a small office and the management provides services such as answering the phone, data entry, typing, etc. You might have something similar in the UK. That way, you could use home-based part-time subcontractors and pay them for what they do and not on an hourly basis. You can also keep up the appearance of a staffed company with the phone receptionist services. I know several insurance agents and accountants who use these types of services.
3. In the USA, the owner of a limited liability company still has personal liability in some situations, so it does not fully protect your personal assets. You also have a company liability from an employee's misdeeds or negligence, but you can protect yourself from that with subcontractors and a good contract.
Andy, what do you do in Japan? I used to spend 2 to 3 months in Japan every year during the 1980s and early 1990s. I really like Japan and the Japanese people.
"It's inexcusable for scientists to torture animals; let them make their experiments on journalists and politicians." -Henrik Ibsen