Posted: 22/10/2014 at 15:55
The seeds from a Royal Gala apple will not grow a Royal Gala tree - apples do not come 'true' from seed. The same goes for Granny Smith. Apple trees grown from seed will also take many years to produce any fruit, if they produce any at all, and they will grow into huge trees and it's unlikely that you'll be able to reach to pick the apples.
If you want tasty apples you need to identify the type of apple you like and then buy a grafted tree of that type. Apple trees are grafted onto dwarfing rootstocks to prevent them growing into huge trees.
If you have a look at this site http://www.orangepippintrees.co.uk/apple-trees/adams-pearmain you'll see an apple called Adams' Pearmain. Let us suppose that this is the apple you like. It is in Flowering Group 3 - this means that when you plant your tree it needs to be near another tree that is also in Flowering Group 3 so that the pollinating insects can carry pollen from one tree to another.
If you look back at that webiste you'll see that there are several apple varieties in Group 3, including Ballerina Flamenco and Arthur Turner. Whichever variety you choose it will not affect the flavour of the fruit on the Adam's Pearmain - it's simply that the pollen from another Group 3 tree is needed in order for the Adam's Pearmain to produce it's fruit.
It's a bit complicated, but I hope I've explained it fairly clearly.