You may need a visa in order to travel to the UK. It is important that you choose the correct visa route based on your main purpose for visiting. It isn't possible to study on a standard visitor visa, so you should obtain either a Student visa (previously Tier 4) or a short-term study visa.
The standard visitor visa is the appropriate visa if you need to come to the UK to attend an interview for a place on your course at London Met, but it will not allow you to remain in the UK to start your studies.