Since you will be sightseeing also, I would recommend the tourist visa. It is fine to attend an induction/conference while being a tourist, however, in order to qualify for a academic visit visa, you need the following requirements, as laid out in paragraph V4.22 in the immigration rules:
V 4.22 An academic applying for a 12 month visit visa (standard) must intend to do one (or more) of the permitted activities set out in paragraph 12 of Appendix 3; and:
(a) be highly qualified within their own field of expertise; and
(b) currently working in that field at an academic institution or institution of higher education overseas; and
(c) if required under paragraph A39 and Appendix T Part 1 of these Rules, provide a valid medical certificate issued by a medical practitioner listed in Appendix T Part 2 of these Rules confirming that they have undergone screening for active pulmonary tuberculosis and that this tuberculosis is not present in the applicant
FYI: Paragraphs 11 and 12 of Appendix 3 (referenced in the same document above):
11 Scientists and researchers may:
(a) gather information and facts for a specific project which directly relates to their employment overseas;
(b) share knowledge or advise on an international project that is being led from the UK, provided the visitor is not carrying our research in the UK.
12 Academics may:
(a) take part in formal exchange arrangements with UK counterparts (including doctors);
(b) carry out research for their own purposes if they are on sabbatical leave from their home institution;
(c) if they are an eminent senior doctor or dentist, take part in research, teaching or clinical practice provided this does not amount to filling a permanent teaching post.
Unless all of these apply to you, you should not apply for a academic visit visa. Even if they do apply, you should stick to tourism because you will be sightseeing, and that may interfere with how the ECO perceives your intended purpose for your visit to the UK.
