The OP says the boy is "light." The HW 100 is quite heavy, with poor balance for a youngster. The S200 Mk3 has a long stock, if you get a Mk2 you can saw a bit off the butt, keep it, and stick it back on as he gets bigger. Better still is the T200 with the adjustable stock. Another good thing about the S200 is the adjustable trigger pull, ideal for smaller hands. Brococks are worth a look, light, but choose the larger cylinder models for a better power curve.
Gus
The ox is slow, but the earth is patient.