Ok... I'm going to try and not repeat what I've posted before, and as I've now found my advanced Spanish course guide I should be able to be more helpful. All of the MML courses are set out in the same way, so everything I'm putting also applies to French. This is the Edinburgh perspective, by the way!
Every week has 4 contact hours- two tutorials, and then two "issues in Hispanism" based sessions which basically consist of literature and films presented in both a lecture and seminar context. The idea is that this way you learn loads more vocab and get more familiarised with the Spanish language. Obviously there is a lot of grammar and other written work per week, along with reading the course texts. We also have several essays (written in English) throughout the course. So its basically about half an half in terms of tutorials v lectures- the tutorials have 10-12 students in and are run by native speakers, which can be really useful, although mine is Colombian and all she ever speaks about is Colombia which gets slightly annoying. Seminars have about 25 people in and allow you to discuss the texts in more detail and pool ideas, and obviously, the lectures have the entire year in.
The Scottish system is quite simple. In short, you need to have 120 credits per year, and each course is made up of 40 credits. The exceptions being medicine, law, teaching etc. Therefore, most people have to follow 3 subjects in their first year to make up the credits. As you've applied for joint honours, 80 of your credits will be taken up by French and Spanish, meaning you can pick another subject to make up the remaining 40 credits. This literally can be any subject, providing it fits in your timetable and there are enough spaces on the course. Most MML students tend to pick linguistics or another language, but if you wanted you'd be able to study English, Politics, Archeology or anything else you felt like. Your outside course doesn't actually feel like an 'extra' subject as you attend the same lectures and do the same work as the people who are doing it as their actual degree, meaning after 2nd year you could decide to change your degree to French and Linguistics, if you felt Spanish wasn't for you after all. I really like the system, Spanish is my outside course and I love it.
Due to being at Edinburgh I don't know anything about St Andrews, but the 3 subject system is exactly the same as its a trait of the traditional Scottish universities.