If you're prepared to look at Glasgow and are wanting a good value, ethnically diverse school, have a look at Pollokshields. However, make sure you are in the catchment for Glendale Primary School - not Pollokshields Primary. And don't assume the catchment - there are some strange dogs legs, so that some of the "big villas", which are closer to Pollokshields Primary, are actually in Glendale's catchment.
It has a good reputation as an ethnically diverse school (60% ethnic minorites, mostly Muslim, but also Russian, Polish, Arabic, mixed race....) and helped develop/pilot Glasgow's anti-racism policies for schools.
However, you might be too late to get in this coming year, as I know it is chokablock and someone coming in to the area, even if they're within the catchment, might now have to go to Pollokshields Primary (although the head teacher does say that there is sometimes movement, with people moving back to Pakistan for example).
Shawlands and Langside Primaries might also be options and given the population of Glasgow's southside, will have an eclectic ethnic mix.