What’s the phone signal like?

It’s been a while since I last went to Download but I can remember it being terrible (like most festivals). My wife has gone into panic mode about leaving the kids and what happens if we can’t call to check in.

I’ve read that some festivals have official partners from mobile companies but couldn’t see anything for Download. I’d be happy to buy a SIM card for whichever network is likely to have best coverage just so my wife has peace of mind that we’re at least contactable whilst we’re there.