tina wrote:
We have a northish piece of land.

The advice you have been given is good, and I would think twice before
getting rid of the pebbly/gritty layer: you may welcome some drainage
in years to come, and it might be useful to double-dig it into the
subsoil before improving the top with compost. Bought in top-soil can
be expensive, depending where you live, while well-rotted horse muck
and stable straw can often be had for nothing for the taking away. The
issue of the grit/pebble really depends on the exact detail of the
makeup, and a few words on usenet might not be enough to get detailed
advice.

So I am going to offer another bit of advice, rather than contradict
the rest.

Join the local allotment association. Unless they are very odd, they
won~t mind that you don't have an allotment, it sounds allotment sized!
AAs are a good source of discount materials, free cuttings,
information, advice, and friendship. Since everyone will be local they
will know a lot about what does well in the area etc.