Cheers Nathu - this stuff (washed Kies) will suffice for the foundation layers to level it out. And they deliver! I am going to order this next week.

All I need next is a couple of tonnes of the Ornamental (nice colours) stones to put on top of a plastic sheet on top of this basic gravel - these will be much more difficult to source at a reasonable price - as you say, they come in small expensive bags which work out a wee bit expensive for the amount I need. It is about 250 metres square I need to fill in around a new lawn I built. I checked lots of internet links last month, but my german badly lets me down when looking for stuff like this.
I think Germany will be best for this - and thanks to the info in the other replies, it now seems that there is no restriction on importing stones and most plants.
If the garden ends up the same way as it appears is in my head, it will be worthy of Groundforce. The right coloured stones will be the deciding factor. I will get there! Thanks again