Looks like I'll have to brave the Leeds traffic system.
Will depend upon the date chosen of course.
May be able to offer transport from Teesside/SW Durham.
Your Mum, unfortunately, is right. Your parents may be more comfortable if they dropped you off and then went shopping or whatever so they can at least meet a couple of people. I used to work within Social Services specialising in child protection and would not let any child of mine meet up with anyone they did not know via an internet or any other communication without ensuring their safety. It's terrible that we have such a culture and fear in this country but its one we have to be aware of and live with.
I'm another who would not be comfortable with under age drinking; at least not in a public bar and without parents present. I'd also be driving
I'm not really a wet blanket but the two points above are important, especially when dealing with people we don't know.
As it looks to be a given that it's Leeds; when? My suggestion would be sooner rather than later as it keeps the momentum up but as with all such things it would be a real miracle if everyone was free at the same time.