Over Christmas, it will be business as usual here.

Well, the expression "Business as usual" isn't an expression I would use this year. Still, it seems right here.

We know that the period between Christmas and New Year is a crucial trading period for our clients. 

So for us, it will be "Business as usual." 

Our clients will be happy knowing they are getting their support as usual. 

We're always here to help. so if you have any questions or need additional advice please contact us as usual.