We have our first proper crop on our apple tree planted 6 or 7 yrs ago. I can't remember the variety but I know it the apples supposed to be sweet enough to eat alone. The apples that have fallen off naturally in the last couple of days are only good for cooking with lots of sugar. There are very few pips inside and that they are white. Does this mean the apples are not ripe? If they are ripe (surely they wouldn't fall off if they weren't), is there any chance the apples will be sweeter in future years (depending on the weather or as the tree matures)?
Yes, the white pips mean the apples aren't ready to eat yet. They might have been blown down by the wind. Apples will also drop sometimes if they haven't had enough water in the summer.
It would help if you could find out what type of apple it is - some apples are best eaten fresh from the tree and some are better after being stored but it depends on variety. But it does sound as though they aren't ready.