If you can stand a pretty technical solution, I check my xmp files into git and my raw files into git annex. I then use the facilities of git to move things around.
If you need a nontechnical solution, then:
- Set darktable to look for new xmp files on startup
- Import raw files into darktable.
- Close darktable
- Copy the xmp files from your laptop
- Reopen darktable and it should give you a prompt about the new xmp files.