Hi there,
It's great that you can do some sketching. That will be really useful for this degree.
In terms of creativity - this is an ambiguous question. There is some level of creativity in all designing however you do not need to be an amazing artist or be able to come up with anything extraordinary for such. You just need to be able to come up with designs you can justify, analyse and present in an appropriate way. In my time in civil engineering, I have had to come up with some roof designs or floor structures which you could argue requires a level of creativity but it is different from architecture where an artistic ability would be recommended. You'll also be taught sketching techniques etc so you don't need to be an expert on such.
Hope this helped,
- Sophie (uni of Bath)