How much work do you want to do looking after it? Shrubs might work well but you would need to keep on top of them size wise. I've borrowed a couple of good books from the library by Alan Titchmarsh about garden design and plants that I strongly recommend. Also the why doesn't my garden book is great too
If you can accommodate a climber, then Jasmine would smell wonderful in summer. For the winter, Sarcococca confusa - sweet box, which has small insignificant flowers in December that have a wonderful scent, and doesn't grow very large.
A cottage garden style would look lovely there. What about a David Austin rose, there are some very strongly scented ones. I would have Hollyhock and cornflowers. Jasmine and honeysuckle if you have somewhere for them to climb.
I saw the topic title and came on to recomend Sarcococca confusa - sweet box but NanTheWiser beat me to it. I have it along our front hedge and it really does smell amazing in winter, it's evergreen as well so can give you structure but also scent in the winter when everything else is a bit dull. I'd be tempted to grow it in a low hedge along the wall just like you would a low box hedge. Perhaps a row of lavender for scent in the summer and a lilac for spring smells.