Hi Rob
Not sure which side of Brum you would be coming from ... but an easy way to reach the site is to leave J9 of the M42 heading down the A446 towards Coleshill. After less than 5 minutes you will have gone over a roundabout, the River Tame and TWO railway lines. As soon as you see some traffic lights, at a T-junction, turn left and you are on Gorsey Lane.
Go right to the very end of Gorsey Lane, passing signs for nearby Coleshill Parkway station and going straight ahead at some more traffic lights, and you are reaching the end of Gorsey Lane with the main quarry entrance ahead of you.
It is important not to go through that entrance, but to park up carefully near the end of GL, where you will see a small stile on the left as you look at that entrance. Go over the stile and in less than 200 metres, walk up on to the raised bank and follow it to the end where it curves round to the right, near a large mound.
From the raised bank, you will be looking over the River Cole. This is your best viewpoint and where you are likely to see any other observers. If you are not familiar with it, Tom Perrins excellent Tame Valley Birding site will be especially helpful.
Good luck if you go ... I have been three times in the last fortnight or so and not dipped (yet!), but no guarantees of course. It's probably best to get there early afternoon and be prepared to stay there until dusk ... a flask of tea or coffee at your side !
Cheers
Andy R.