How practical is this sort of thing if you're working on your own, not that I know whether you would be?
Do you mill where the tree lies after it's felled or do you need to be able to extract to somewhere else. I see they have the it sitting on some supports which means they can cut right down to the very last piece.
What sort of setup would you need for drying/seasoning?
I'd only manage the operations required, hiring appropriate experts, not doing the specialist bits myself. To hire tree fellers should work out at an hour each/ £50 a tree if they do several in one visit. The trees need to be carefully moved using a tractor and log arch to a firm flat processing area for cutting (I have one on site- my former gypsy site, thank you Council for filling in my pond and creating 1/3rd acre of hard standing). If they are just dragged, grit gets in the bark which will screw the mill blades. I can hire a local Peterson Mill and operator for £350 a day, who could process a good amount in one visit. The advantage of a Peterson v Woodmizer is it gives a very straight cut on hardwoods, woodmizers use a bandsaw which can wobble and give less even cuts. If selling at a premium to the likes of cabinet makers, you need top quality good clean cuts. The market for English Oak boards of this quality is strong, its very much in demand. Because it grows slowly, its far superior to Continental Oak.
Hardwoods can be aired dried in the wood on site if carefully stacked with spacers and covered on top to keep the rain off. There are also solar drying 'kiln' set ups, where you put something like a polytunnel on the drying stacks, and use the power of the sun to dehumidify. I'd read a couple of pieces about this and have been referred by the Peterson Mill guy to someone who does it professionally in another region, who I understand is very forthcoming with info, might visit them. I also know a local wood worker who has a large heated wood drying kiln, it would be possible to speed the whole process by renting his facility, as he's offered. The cost is not prohibitive, and it might also be possible to consider a similar small facility on site using something like a shipping container; the sealed unit is heated to about 40 degrees and a electric dehumidifier used to extract the moisture, the process then takes weeks rather than months or years. The natural air drying process is cheaper though, has less carbon footprint and doesn't need electricity.
This approach does require quite a bit of time to research and supervise, the right level and secure physical space to process and store finished timber, an initial outlay for the labour/equipment hire, some time to devote to marketing & selling, and the commitment of quite a lot of personal effort and free time.
Its easier to just sell the whole tree at the roadside, most people can't face all the hassle of seeing this from start to finish; its like do you grow Barley and sell it as grain or open a micro Brewery? As I understand it though, the difference in income if you see the whole process through with a tree is a factor of five or more. A tree's worth of dry quality hardwood oak boards is worth many thousands of pounds.
Its certainly worthy of further investigation.