The answer is that you can't expect them to come true to type from seed. By far the best way to obtain large numbers of one variety is the layering method. The downside is that it takes a couple of years to get enough to do anything with.
You can obtain seedlings here:
http://www.agroforestry.co.uk/plantorders.html And in bulk here:
http://www.ashridgetrees.co.uk/Common-H ... s-avellana
Fora hedge you need to think about planting 3 to 4 feet apart and staking between and then ethering the tops together. (You don't say if it needs to be stock proof). after about 5 years it can be "laid", all the main branches and stems are best part cut through and laid over (Usually uphill) then stakes and ethers hold it together. Ethers are long whippy hazel rods which are wound into the top of the hedge as it is laid over.
You don't usually plant seedlings/layers until November when they're dormant. You may also need Rabbit/deer protection.
Another thing that comes to mind is a "Nut walk" where trees are planted about 4ft apart in 2 rows 10ft apart to provide an arched canopy where the nuts can be collected from underneath. It also affords good stick yields for loads of country uses.
Time flies like an arrow; vinegar flies like an uncovered wine must.
