About a year ago I decided a silver birch would be ideal for a
particular spot in the garden, but because our garden is only 35ft x
21ft (with another house directly siding onto the bottom of it), the
tree will have to either stay below about 20ft or be cut down when it
gets there.

Looking on the web, it seems no site can agree what size different
cultivars grow to. The "Snow Queen" looks as if it would do according
to some sites whereas others put it 3 times bigger!

Also I can't find a supplier who a) has them in stock and b) can
deliver. I know we can't get one locally, so it would need to be
delivered.

Is there a service I can phone up and ask them for a specific type of
tree and they'll source it, deliver it, and plant it for us? I would
have liked to get one that was already about 10ft or so tall.