Silver Birch trees can get quite bit - though they are generally shallow rooted - my neighbour's one is taller than our house now and it was planted about 10 or 15 years ago.
One of my favourite shrubs is a Choisya ternata (the green rather than golden version) - Mexican Orange Blossom - evergreen, tolerant and can be clipped back to what ever size you need once a year - and fantastic smelling blossom. If you want a tree what about a Japanese maple - I have one - nothing fancy - just small green leaves, that is now about 8 ft tall and it is growing in a shady location - though not sure what it would think of sandy soil....
I like that one Summerdays and on the web it says
If your soil is slightly acidic, sandy, well-drained loam with a good amount of organic matter, then you have the perfect conditions to grow Japanese maples.
It also says it has fine roots and can be grown in pots, if you pick the right variety. Likes shade too, otherwise it gets leaf burn. Sounds perfect. I'm swinging back towards a tree there. And my soil is sandly, well drained due to the fact it's not far from two soakaways and well watered from one soakaway.
Like those bushes too. I might have a place in my back garden for them or the ones Rich suggested. I think I'll need to find them in my local garden centre.