As Stoneleigh is near me I know the local roads, so this is a courtesy post for those who haven't been before:
> Stoneleigh is just off the A46, a busy dual carriageway. If you're accessing the A46 North from the M40, come off at J15 towards Coventry.
If you're getting on to the A46 North from south of Stoneleigh (from the M40 or from Stratford-on-Avon), you need to exit the A46 at Kenilworth / Leamington Spa and follow the signs towards Leamington (third exit off the junction) - the route to the show will be well signposted.
> If you're coming south on the A46 from the Coventry side, DO NOT exit at Stoneleigh as you won't be allowed to go through Stoneleigh village and will just be redirected all around the houses, wasting 15 minutes you'll never get back. Your best route is to go to the next junction south (Kenilworth / Leamington Spa) as above (first exit at the junction). NOTE: The police just love to park their speed camera van on the bridge over the A46 at the Stoneleigh junction facing north, and pick off speeders as they come around an unsighted curve - watch yourself.
The good thing about going this way is that you'll be on the correct side of the road for the show entrance. The alternative route from the A45 at the BP island and down the B4113 is pretty enough, but you end up queueing to make a right-hand turn across traffic to get in.
Finally, there are considerable roadworks on the A4600 South (Coventry Eastern Bypass) between the Binley roundabout (B&Q, TGI Fridays) and the Coventry Airport roundabout, and on the A45 from the airport roundabout to the A46 junction, with average speed cameras and almost certainly bank holiday traffic delays. I would suggest avoiding this route if possible but if you can't avoid it, allow an extra 15-20 minutes as a buffer (and make sure your cooling fan works!).
> When you finally do make it in to the show, drive straight ahead after the entrance gate and you'll see our stand on the right after about 150 yards, impossible to miss. Turn right before the grass and follow the parking assistants directions - they may look mad, but they're great people.