Grandmabatty
I thought about a Box. I have never heard of Christmas Box so will Google. I have just picked up a David Austin rose- Desdemona - to put in the pot for now, however I'm happy for all suggestions as the rose can go somewhere else.
I was going to suggest a rose, David Austin bred roses are often great for pots. They did an article about this recently and Desdemona was recommended, it’s one of my own favourites.
Rather than box you could try Euonymus japonicus 'Microphyllus' which looks similar to the box used for topiary but doesn’t get diseased. My Christmas box is easy to grow and healthy but doesn’t have a scent. Some varieties are much more interesting looking than others.
Another evergreen option could be camellia sasanqua which isn’t very strong hoeing. I’ve had a healthy one in a pot for five year now and it’s worked well. You can get various colours and it flowers in late autumn/winter. I don’t think it would work if you’re east facing as sun would spoil frosty buds. Although it’s ericaceous I use tap water with a splash of acidic feed if it needs watering. Some little ferns have self- seeded under mine in the pot.