When I started University I had similar doubts about doing Software Engineering, I chose not to going for a more generalised Business Studies with Computing.
8 Weeks in I regretted not doing Software development, I changed course to a more general computing, did all the programming I could, (all in games development), I did my work experience abroad, I came back and I finished my degree with the less than perfect score I was expecting in the less than perfect course for a software developer.
Ended up I got a job as a software developer creating and maintaining works management and finance software (not games at all)
All in all I see my own time at University and indeed most of my life a serious of mistakes, misjudgements or accidents one after another.
At the end of the day I still learned to program, I still ended up doing what I enjoy, had at any stage I not enjoyed it I'm sure I would have found a way to muck it up :)
Computers is a good base degree to have anyway, it should provide the "check box" that a university degree is to most employers, with the benefit of qualifying for the "Computer related degree" after that experience or proof of knowledge is what they look at and you get experience doing the job you want to do for the cheap wages as a graduate or trainee anyway.
As for not knowing much about programming, its their job to teach you if thats where your course leads!
And so I surmise that it really doesn't matter as much as you think, Don't try to look too far ahead.
And for any other advice please see.
"baz luhrmann - wear sunscreen" lol to quote from it
Don’t feel guilty if you don’t know what you want to do with your life,
the most interesting people I know didn’t know at 22
what they wanted to do with their lives,
some of the most interesting 40 year olds I know still don’t.