Year 3 and 4 players

Are you asking whether Year 3 & 4 players can take part?  I would say Yes, the more the merrier.

Tag Rugby is a Non-Contact Sport.  So Age and size difference should not matter.  Though generally speaking Year 6 players can be significantly faster than Year 3 pupils (sorry to generalise)/

Having said that, last year, the winning team - Sevenoaks Primary - had Year 6 and Year 5 Boys.  The girls in the team however, were all Year 4.

Hope that covers it?