Regarding the date/time of the games, the fixtures list all games as being on the Sunday, but due to TV broadcasting, they are spread out over the Saturday and Sunday, with one game also on the Monday. This is announced on a weekly basis, about 10 days in advance.
As for buying tickets, unless you're getting a very good deal with a hotel, you will be better off simply buying your tickets online yourself. The official site doesn't accept UK credit cards, but you can reliably buy them from http://www.servicaixa.com - this offers the same seats that the official site does, and at the same price. This is bank's website, and you print the tickets at one of their cashpoint machines when you arrive in Barcelona.
You say you want "tickets" - it will likely be impossible to buy two or more seats together now. The best you can do is to find them close together in the same block. However, a few days before the game the seats given back to the club by season ticket holders will go on sale, and you may have a better chance then to find adjacent seats.
As for buying tickets, unless you're getting a very good deal with a hotel, you will be better off simply buying your tickets online yourself. The official site doesn't accept UK credit cards, but you can reliably buy them from http://www.servicaixa.com - this offers the same seats that the official site does, and at the same price. This is bank's website, and you print the tickets at one of their cashpoint machines when you arrive in Barcelona.
You say you want "tickets" - it will likely be impossible to buy two or more seats together now. The best you can do is to find them close together in the same block. However, a few days before the game the seats given back to the club by season ticket holders will go on sale, and you may have a better chance then to find adjacent seats.