Hi FF. Probably not what you want to hear, but I think they are pretty difficult to get hold of in the UK as they haven't been made for years. There are some really cheap and nasty copies sold by some army surplus shops, but I would avoid them.
If it's an actual Demo knife she wants, the best bet will be flea markets etc. If she wants that 'type' of knife, the Wenger Standard Issue, Victorinox Soldier or Pioneer has exactly the same tool set with much better fit and finish, and is still available quite cheaply. I have a Wenger SI and can't recommend it highly enough. Absolutely bomb proof.
Sorry can't be of more help. Maybe you'll have more luck appealing to our US contingent where the knife is more widely available