Combined honours degree? Do you mean a joint honours (where you study two subjects eg. philosophy and politics) or what Durham call combined honours (its own degree where you can study two or three subjects each year in the arts and social sciences, creating your own programme?)
I'm assuming it's the former? It can depend on a number of factors. Firstly how competitive the course is and whether you meet the A-level and first year requirements.
I changed from single honours philosophy to JH PhilPol after my first year. It was quite simple, I just wrote a personal statement and, after getting the departments support, sent it off to the Dean and it was granted. I did cover enough politics modules in my first year (two) in order for me to cover the required pre-requisite modules needed to proceed to the first year.
So, if you want to change to a JH course at the end of the first year you need to make sure you've covered any required modules for the department you're transferring into. If you do
If you're talking about transferring degrees within the first few weeks then this is usually easier (as you don't need to worry about pre-req modules). You'll need to inform your college and department in those first two or three weeks and, with the support of the department you want to transfer into it should be possible.
All degree programmes have space on their courses to allow students to transfer. But competition can still be intense depending on the department.
If you were actually referring to what Durham call "combined honours degrees" then I think you still can transfer. I've heard from a fellow student that it's the one degree you can't transfer to but my senior tutor assured me you can. Space is very limited (it's one of Durham's most competitive courses so already quite full) and competition is fierce.
If you want a clearer and more succinct answer then you'll probably need to wait until tomorrow. I'm really in a strange rambling mode tonight (being a mod and dealing with trolls takes its toll
) and probably just confusing you. Someone else could explain better anyway.
Sorry. Try and be back tommorrow. Do you have doubts? Are we talking about a specific JH degree here? If so then I could give specifics.