Some of the most impressive bathrooms I have seen are those with an antique cabinet as the vanity. In some instances the basin is of the sort that can simply be seated on top of the tabletop, and others have actually been cut into in order to install a sink. But, boy oh boy do they make an impact either way.
The best part is, this is something that a homeowner can tackle on their own. However, it is most certainly understandable if you would prefer to opt out of this activity and to leave it to a professional. Chances are they done this exact sort of thing before, and can do it all in a jiffy.
To get the show on the road you will need to first find a wonderful cabinet, or table with drawers FYI, this is not for storage, but to conceal the plumbing so keep that in mind when evaluating the depth and width of the piece of furniture, along with the drawers. Otherwise, you might just find that you are the proud owner of a lovely old article of furniture, that is not useful for the purpose for which you bought it.