You can become an art valuer byworking in an auction house or antiques business as an assistant, porter, or cataloguer and learning through experience and part-time study.
Alternatively, you could join a graduate training scheme with a large auction house such as Sotheby's or Christie's – only a few of these are offered each year, and you would usually need a degree in a subject such as history of art or fine art.
You could also do a degree in a relevant subject, such as art history, fine arts and restoration, or fine arts conservation, followed by further professional training in valuation.
To find a relevant degree course, use the course search on this site and check with individual institutions for their entry requirements.