Birchfield, st Gildas, st Michaels and Oaklands do serve the more deprived areas of Yeovil, that is true, but good leadership and good teaching has made a big difference to those schools.
I would choose the best school you can get to by walking there. St Gildas although is a good choice, getting there is a pain in the neck.
If you have able, more academic children then I still say Oaklands or birchfield. But the other poster makes a good point as birchfield dies feed into bucklers mead and I personally do not like that school. Preston is better.
St Michaels, pen mill and Reckleford probably serve the poorest and most challenging catchments, and have quite needy children.
I think you have to go with your gut.
I do know that birchfield has very good teaching and the children are well behaved in school. It does sit in an estate but who cares?!
Milford infants is ok, juniors, I don't know.
It's such hard to know what to do!