Whilst we do not know a huge amount about track construction ourselves, we are in the process of putting in over 800m worth of rides and track in our 6 acre wood, so I will share from our experience.
PLANNING: Don't forget that, aswell as permitted development plans, "applicants must always seek an opinion from the FC on new forest roads." In our case we needed to have an Environmental Impact Assessment done as well. The regional FC Officer was extremely helpful and sorted it all out for us. Our local council Forestry Officer was equally helpful in advising us on ride/track layout and local contractors (and then reasuring us that the contractor was not being unreasonable when he recommended over 2 1/2 tonnes of stone per running metre of a 3 metre wide track.) And when we had an unexpected dry spell, the Planning Officer pushed things through in a couple of days so we could take advantage of the weather and get the contractor on site! We were concerned that the authorities would think it was overkill for a wood our size, but they were delighted because it showed we intended to manage it and they did all they could to help.
TRACK CONSTRUCTION: Now I don't know about building tracks on sand because we are in the unenviable situation of working on a wet site with clay topped up with a thin layer of peat, but I think it strange that you are going straight to MOT Grade 1 - everything I have read talks about needing a solid sub-base first. Maybe sand counts as a solid base, but it may be worth looking into that. In our case we started with 2 tonnes of '100mm to dust crushed stone' per running metre, but after a couple of loads it was clear that was not large enough so we completed the foundation with '150mm and down'. It seems like overkill, but even that will only take domestic traffic (i.e. cars pulling a tonne of logs, caravans, school minibus) and not cope with heavy felling machinery. We now have a good firm sub-base which has been allowed to settle for a month or so. Next week it will be shaped and rolled before being capped with 64 tonnes of MOT grade 1 over 100 metre. The stone is the expensive bit if you cannot quarry it on site. We did talk about using a membrane to save on the quantity of stone used, but in our situation we decided to reduce the length of the track and go for the strongest contruction possible. This is a one-off capital expenditure that we allowed for when purchasing the wood and we expect it to outlive us. I found the following FC article helpful
http://www.forestry.gov.uk/pdf/ON025-Fo ... 110809.pdf DRAINAGE AND RIDES: Although the main track has been by far the biggest expense, the biggest impact has been having the contractor clear a network of rides and drainage ditches. It only took a couple of days (@£30/hour) and was the best money we spent. Now we have access to almost all parts of the wood and when they have had a chance to dry out enough for him to do the final grading we will let the grass grow back. They should then be dry enough for year round access with a trolley on foot and a car in the summer. A few hours work and 1/4 acre of brash has been swept away, all the tree stumps left from the clear-felling operation dug up and buried deep out of sight and the site roughly levelled. We had started to clear this area but after a couple of days of hacking away we had barely made an impact. Half an hour with the tractor yesterday saw the area rotavated and levelled even more - it would have taken us days to do it with a small domestic rotavator. Now we are left with a large level clearing to sow a wild-flower meadow. I have been won over with using large machinery to do the big jobs. One things we have come to realise - owning a wood is much larger scale than gardening.
Warning - it looks a right mess when it is being done, but even now we can see the grass growing back and it looks better.