Help wording surprise for 21st

[Justtheoneplease]

Hi, can anyone help. I need to work out what to write in a card for a surprise trip to London for a show. I'm going to get tickets for a show she's been wanting to see for ages. Date can't be confirmed until after the surprise due to work commitments. It's for my neices 21st birthday. Please help as stuck and need to get it sorted soon so I can get her card posted. Thanks.

You get personalised scratch card gifts on Etsy and NOTHS etc. A5 size and pretty.

Thanks but it's the actual wording I'm trying to find, I've looked on NOTHS and Etsy but nothing suitable. I just wanted someone with a bit of artistic flair to help me compose something.