GPS system for Countryside Productivity Small Grant Scheme SG40 and R2-SG77

I really need a GPS for drilling with Case Magnum 7120 (M reg) pulling a 4m Great Plains direct drill. The drill is over 8m long, so not really an act of war to turn back on myself on the headland! Ideally could do with a system that could be switched to my other tractor (Case Maxxum MXM 120 '03 Reg) for other jobs

I applied for the GPS/Autosteer system option under the Countryside Productivity Grant Scheme thinking a 40% grant (comes to just under £1,300) would be handy - details from...

GPS system for Countryside Productivity Small Grant Scheme SG40 and R2-SG77