Regular drivers from nw to Switzerland here. Always drive across to Hull and get the overnight ferry to Zeebrugge. Then head down through Luxembourg and eastern France to Basle, though depends on where in Switzerland you’re going. Dont forget to buy your vignette, you might need another one for the trailer.
Edit.. Sorry, you do say Davos, so better to come down through Germany and come in either past Zurich or through Liechtenstein. The former is slower but more scenic. You can still start at Zeebrugge.