Many activities are open to people from any department to participate with no specific skill-set required (such as LSE GROUPS or LSE Change Makers). These are often the activities that aim to foster interdisciplinary inquiry.
Other initiatives may be particularly attractive to students from certain departments, but are, in fact, open to all (Posters in Parliament, for example, which often appeals to students in the Department of Government).
The departmental internships are usually only promoted among the various departments’ individual cohorts. If you wish to apply to an internship which is offered in a department other than your own, contact the department to ask if this is possible. If your area of expertise or skill-set fit the role well, then there is a possibility that you will be considered for it. Some internships offered, for example, by the US Centre, recruit students from a variety of departments (International History; International Relations; etc.) whose work relates closely to that of the Centre.
Sometimes a specific skill-set is needed (the ability to speak a particular language, for example); but for other roles, supervisors are more than keen to teach new skills, and all that is required is a willingness to learn!
The student journals focus on specific areas of research (politics; philosophy; information systems; etc.) which may or may not align with your areas of expertise. However, there are many of them! A number of journals, too, are open to submissions from researchers with expertise in aligned and complementary subject areas that may be a little 'outside' of their core focus. If you have an idea for a submission and you are unsure about the subject match, ask the relevant editorial team.
Click through to an opportunity in one of the opportunities sections here (activities; internships) or contact the relevant department or centre for further information.