Urgent! Tipping at stables?

[Arcadia]

My DD has her bday party at her usual stables where she has lessons this afternoon. Already paid for. Would it be odd/unusual to tip the teacher who is going to be taking the party?. I know it is usually her day off and she has had to step in, and has been lovely asking DD what she wants to do etc. I was thinking of slipping her £10/£20 in cash at the end as I know they are not well paid, or is that not usual at stables?

Too late now, but I would be inclined to take in a nice box of chocolates by way of thanks rather than tipping. Chocolate is the generally accepted currency of grooms and riding instructors.

Thanks cali in the end I just slipped her a £10 note at the end and thanked her, as I knew it was usually her day off. She seemed pleased and I didn't get the sense that it was inappropriate. The kids had a great time!