hi, I live on Graham road, and until we moved here last year we lived on Southey road for 5 years. I think it is a great area, lots for kids to do and excellent transport links, but perhaps not as many parks as you would wish. Your nearest would be South park gardens, just a few minutes' walk but no play area or games for children.
If you are close to the broadway you may find it noisy at nights. There are some nightclubs nearby, but I lived on the corner of Pelham and I never heard anything.
Pelham school is going to be expanded this year I think, so I would check what the deal is with the planning permission and whether this will affect you at all - though obviously that would be a short-term inconvenience only.
If you are practising Catholics, one alternative would be St Mary's school which has an outstanding Ofsted, but you will need a letter of reference from your priest.
If you ring the Merton local authority and give them the address, they will list what schools are your nearest, and you can then check catchment areas for these schools to see where you might get in, but your best/only bets will be Pelham and St Mary's, which are both very decent.
Good luck and feel free to ask if you have other questions.