Thanks girls! I think I may put 'Jersey Boys' in the 'too hard' basket! I just checked out a couple of websites - I thought a Wednesday matinee would have been the best choice but there are far more seats available for night performances which I'm not keen on. The cheapest are those on broadwaybox.com (as originally suggested by Doug) but they are 'second hand' (forget the correct terminology). I presume these are safe to buy - don't think we're allowed to do that here!
Thanks to everyone for all your help.
Anne: As the worst hostess in the world, I look forward to seeing you again on FJORDS and hopefully I can offer you at least a cup of coffee on board! Let's hope the weather is better this time!
Lee