前往Imperial College London的身分問題 - 留學

我是一位台灣的博士生,
我將前往Imperial College London進行訪問研究,
而對方要求我要申請"occasional student",
其信件內容為:

You will need to make an application as an Occasional Student.
You will require:
* ATAS (as you are coming to study for more than 6 months)
* A Student Visa
* English language qualification to meet UKBA requirements
You can make an application as an occasional student,
and you would then need to get
ATAS (20 working days) and a visa (probably within 10 days of application).
Your application can be made here:
https://apply.embark.com/grad/imperial/visiting/13/
and please choose option 6 - Doctoral level study

這個"occasional student"似乎是校內的稱呼.
那不知道這要不要繳學費呢?
另外, 我的visa就是比照一般學生辦理嗎?

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