Hi there
Stayed in Salou last September. Port Aventura is on the main railway line but so easy to get the bus there.
To get to the football ground get the train from Salou costs about ten pounds for adults return not sure about little ones as our two boys were under five. Takes about one and a half hours, then get the Metro to the ground ,forgot the name of the station but someone can tell you. Then about a ten minute walk to to the ground.
Excellent tour round the ground cant remember how much we paid but it was money well spent as my wife hates football but was in in ore of the Neu Camp.
Cheapest option Salou

hi Happy One, Thanks for your help, its sound quite straightfoward although we would probably get lost! Did you prebook the tour of the football ground here or do it once you were there? It would be my boys dream to actually watch a real match there, but I think at aged 8 and 4 they are a little young! Maybe in a few years time! Did you like Barcelona itself, or prefer Salou?

Hi Jen06
You don't have to pre book the Neu Camp, you buy your sightseeing ticket at the ticket office and then do the tour at your leisure.
The route is taped off but you get to see all the important places at the ground. Lasts for as long as you want it to. We spent about two hours going round.
We went to Barcelona after but only went down the Rambles which is the main walk down to the Cathedrel, loads of shops and cafes and also these human statues which are very good but you have to pay to take there photo.
Of a choice we loved Salou and are going back for two weeks this year.
We stay at Sanguli campsite with Thomson Al Fresco brilliant.We are about a mile from the town but its a lovely walk along the beach or if we are lazy we get the bus. hope this helps

See if you can find out if there is a Barca match on when you are there because if not it would seem silly to stay in Barcelona and travel to salou if you are only going to look around the Nou camp.
Getting to Barcelona from Salou is easy, there is a bus runs throughout the day, its reasonably priced too for a return ticket. You can get the train but be warned they can get packed or if you didnt feel confident to make your own way you can book trips with the reps to Nou camp, this often includes a trip to the zoo or shopping as well as a tour of Nou camp.