You could either direct-collect the leaves or use a tractor-mounted blower to blow the leaves back to woodland edges or to form a windrow for collection by other equipment.
If you want to collect the leaves you could use a ride-on collecting mower. The Etesia Hydro 124, for instance, is noted for its powerful lift that will send leaves streaming into the 600-litre rear hopper. With the high-lift version, you could empty straight into a trailer. Etesia also offers brushes for fitting to its ride-on mower range.
There are other ride-on mowers capable of lifting leaves into a collector. Using a mower means the grass gets a clip at the same time and the tractor remains free for other duties. But tractor-mounted mowers with collectors are another option. The flail-type collector machines are really versatile and can be used as scarifiers, collectors or mowers. You might look at those offered by Amazone, Wessex or Wiedenmann.
There are a number of large vacuum machines for use behind tractors. This is the type of kit regularly used at golf courses and other large-scale grassed areas. One of the best-sellers in the UK is the Trilo range - with hopper capacities from 400 litres to 11,000 litres. The powerful vacuum created by these machines means they can be used for clearing up after concerts and rallies - they can clear beer cans and bottles. You can also use them to collect debris after scarifying operations. An alternative to the Trilo might be the Favorit vacuum collector from Wiedenmann UK.
Opting for a brush-type collector will save pounds over a vacuum unit. I would suggest you look at the trailed Litamina units from Sisis Equipment. There's a choice of sweeping widths up to 1.83m and hopper capacity up to 2,000 litres.
While handheld blowers may be too small and labour-intensive for your operation, it might be worth looking at wheeled blowers. Some have tremendous power to shift leaves. When we tested the Billy Goat Force we found it took just five sweeps to completely clear a football pitch of autumn debris. The Kersten Vento would be another I would add to my demonstration list.
For really large-scale operations, the tractor-mounted blower takes some beating. Again, there is plenty of choice. We have tested the Tornado from Turfmech and found it will shift leaves, scarification debris and aeration cores. We have also tested the Buffalo KB3 towed blower, imported by JK Inc. It has an impressive maximum air speed of 83m/s. Others we hope to look at this autumn are the Trilo, Bargam, Whisper Twister from Wiedenmann and Windstar by Ransomes Jacobsen. And JSM Distribution is set to import the AgriMetal low-decibel, tractor-mounted blower.