The starting schools guidance booklet from the LA gives you a map of the primaries, how last year's places were allocated including maximum distance, and the number of places available for 2019 start. Spaces do come up at primaries if you've missed the application for Sept 2019 start. Maybe Sutton council can advise on where there are currently spaces for the year(s) that you need.
https://drive.google.com/file/d/1SDZI4k ... WVmM9/viewThere are some good non-grammar secondaries if needed further down the line. It may be a good idea to check out locations that would ensure you're in-catchment for the excellent brand new Harris Academy in Belmont, or Overton Grange, Cheam High, Glenthorne, Carshalton Boys, or Woodcote High just across the boundary in Croydon Borough. There's a list of secondary schools here:
https://www.sutton.gov.uk/info/200439/s ... l_year_7/2This is how secondary schools were allocated on distance on 1 March 2019:
https://drive.google.com/file/d/11RP224 ... NGlPH/view