Hi Simon B, hope all is well! Check out "Contemporanea" pandeiros, the best!!! Both 10" and 12" are the more common sizes, although 12" pandeiros tend to be a little heavy for the beginner. Contemporanea offers both wood (choro) and formica models (more popular on the Escolas de Samba). Pandeiro soloists like Marco Suzano, Airto Moreira, Guello, Paulihno Silva, among others tend to prefer the lighter 10" wood "Choro" pandeiros. Check the Contemporanea line at:
http://www.brazildrums.com
Hope this helps!
Saludos,
Jorge Ginorio
http://www.congaplace.com/musician/jorgeginorio