I had the pleasure to shoot at Wembley yesterday. By far the best stadium I've been to so far...
Getting there
Predictably very busy on a match day, but get there early. I was on the motorbike and parked in the Green car park about 20 yards from the photographer's entrance (just to the left of the "Wembley Way" bridge under the concourse).
Get there early because all the photographers also get there early. I checked in, did the bag search and got my creds, then onto the Photographers Lounge. As a first timer I asked where to go and a nice media steward took me through.
Once in, the advice is to get pitchside and book your place pronto by laying down your monopod/stool. I did this at 2pm (5pm kick off) and most of the good spots had already gone.
Getting away is predictably very tricky too if you are in a car. Expect a long slow dribble out of the estate and onto the main roads. By motorbike I was back in Guildford in 40 mins

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Comms & Power
In your creds pack is a bit of paper with login details for the network connectivity. Dont lose this! In the Photographer's Lounge there is wired network and power. Rather fantastically, you can get the same pitchside as well. There are wired LAN ports all around the pitch. There are also numerous large plastic boxes full of LAN cables as well. If you sit near one of the covered green power units you can plug in your laptop too. Some togs take an extension lead with them as well. The networking is awesome - snap, caption, send. I was pinging pictures away 2-3 mins after taking them. Bloody brilliant!!
Lighting
I was there in daylight. There's a pretty harsh shadow that comes across the pitch but that's nothing unusual.
Other Stuff
You'll get a wee bag with sandwiches, crisps, chocky and a drink. Also there were hotdogs post match. Tea and coffee are on tap and there's a fridge with cold water in. The staff are exceptionally helpful. Overall an excellent experience.