For anyone interested, I emailed to ask and this was the response - hope it helps some others too:
(sorry for the awful formatting - I've copy and pasted the email and it didn't like that, even when I went through and put paragraphs back in!)
As you are studying towards an MA(SocSci) degree, the majority of your credits should be social sciences (Sociology and one other social science in Years 1 and 2). So two of your three subjects will be Social Sciences (I’ve marked them (SocSci) in the list below).When choosing your third subject in Years 1 and 2, you can have a little more flexibility.So, first off, we don’t offer any of these vocational degree programmes as a third subject:Accountancy & Finance, Dentistry, Education (Teaching), Engineering (all disciplines), Law, Medicine, Nursing, Veterinary Medicine & Surgery. The degrees above don’t follow the flexible degree structure, and would be similar to equivalent degrees in Northern Ireland, England or Wales. Other subjects that would not be available as follows: Accounting & Maths, Accounting & Stats, Finance & Maths, Finance & Stats, Community Development, Electronics with Music, Film & Television Studies, Music (BMus), PerformanceTheatre Studies, Psychology (our most popular subject, priority goes to applicants with Psychology as their first choice), Any course at Dumfries Campus. Subjects that MAY be an option but are very popular: Business & Management (SocSci), Business Economics (SocSci), Central & East European Studies (SocSci), Economic & Social History, Economics (SocSci), English Literature, Geography (SocSci), History, History of Art, Music (MA), Academic Study, Politics (SocSci), Social & Public Policy (SocSci). Subjects that will likely be an option: Arts - Archaeology, Celtic Civilisation/Celtic Studies, Classics, Comparative Literature, Digital Media & Information Studies, English Language, Gaelic, Greek, Latin, Philosophy, Scottish History, Scottish Literature, Theology & Religious Studies. Modern Languages - French, German, Hispanic Studies, Italian, Portuguese, Russian, Spanish. Sciences - Astronomy, Chemistry, Computing Science, Earth Science, Geography, Mathematics, Physics/Theoretical Physics, Statistics. This is the list as I understand it! As priority for places goes to students who have applied to that subject, we won’t know for sure what subjects will have spaces available until A-Level results day. All options are subject to availability. Access to science subjects may also depend on your A-Level attainment (holding a relevant A-Level in that subject area). Your Adviser of Studies will be able to give further guidance when you register to begin your studies at Glasgow.