Cheers mate and
@ysmsa too. After reading both your posts, I've decided not to risk this route as while getting back to Birmingham shouldn't be a problem, I've only got one Birmingham to Manchester train to aim for if it goes to extra time and pens. With us being at the wrong end of the stadium, I can see it being a lengthy wait to get on one of those Birmingham-bound trains. I'd need to be out of Wembley and on the train by around 7.30 to make that last 9.57 train back to Piccadilly. If it's ET and pens then the match is probably only ending at 6.20 or later and I can easily see it being another hour or more to get on a train at Wembley Stadium station. If we'd been given the West end of the stadium, I'd have probably risked it.
I've decided to go via Leeds instead. I said last night that there's a planned strike that day that may effect some TP Express services and for that reason, Leeds was out, but silly me forgot that Northern run trains to Leeds as well from Victoria which increases my options. So I've booked Leeds - Kings Cross going out at 9.15am and returning at 7.33pm. That may be tight as well if it goes to ET and pens but my experience of the tube is that while Wembley Park station is hammered afterwards, the queues tend to move quickly. There is some wiggle room if I miss the 19.33 as there's another about half an hour later, and if I make the 19.33 I should have up to 5 trains back to Manc to choose from when I get back to Leeds. I'm also hoping that if it finishes in normal time and I get back to Kings Cross early, they might let me on an earlier train. They often do this at Euston for games at Wembley and bung you on whatever train is in. Whether they would do this at Kings Cross I don't know.