The easiest approach is via the M1:

• at junction 28 take the A38 towards Mansfield
  
• at the 7th set of traffic lights, after about 4.3 miles, turn left into Coxmoor Road (if you pass a reservoir on the right or reach B&Q you have just passed Coxmoor Road)
  
• G.T. Tools is 50 metres on the left

To plan your route, try the AA.

If you are arriving by train at Derby station:

• follow signs to Mansfield (A38)
  
• stay on the A38 as it crosses the M1
  
• at the 7th set of traffic lights turn left into Coxmoor Road (if you reach a roundabout you've gone too far)
  
• G.T. Tools is 50 metres on the left

To check train times, try Railtrack.