hey nice to hear ppl from all over the world coming in manchester!!
first of all piccadilly square is about 20minutes by bus. you'll take bus No250 you'll stop in front of old trafford's north stand! if you want to get there faster you'll take metrolink from piccadilly square too, i dont remember the number but it is altringham's metro. it's will take you there in 5 minutes but you'll need 5 more minutes walking. ask the ppl there if you have any troubles for directions.
you must be in the stadium at least 15-20 minutes before the kick-off. after entering the stadium you can watch MUTV pre game show in LCD tv's or have a pint or just take your seat. the tickets are numbered as RD said so if someone is seated in your seat you can just report it to the security staff (i hate these guys!!!).
as far as your stay i suggest you to stay in manchester. london is a 6-hour trip by train and i dont know if there are any schedules for midnight times. some good hotels and cheap in manchester are ibis hotel, britannia and gardens. all of them are on the piccadilly square and very cheap. i paid ~150pounds/night for a 3-bed room in gardens hotel. i stayed with other 2 friends so i paid ~50pounds/night.
in all terms you will have to stay in manchester!
for the night you'll go to the printworks clubs! smoking is forbidden in any place except the roads so if you smoke i suggest you to buy warm very warm clothes and prepare to smoke under the "moon light"
these are my advices. if you need anything else just write down or send me a pm.
oh i forgot to say that as long as you are going for the first time in old trafford take the museum and ground tour. i suggest you to get to the stadium 2 hours before and have a walk around the stadium. there will be plenty of things to buy
