Gift of £50 or so for late 20s woman in work situation

[Legoless]

I want to buy a thank you gift for someone who had helped me out in a work situation. I don't know much about her except she is posher than me (not hard!) in an industry that is quite luvvie - think art gallery type job. She is junior-ish so won't have hugely high salary. I was thinking about £50. Flowers too ephemeral and chocolates/biscuits don't seem massively appropriate. What would you send? I don't feel comfortable sending a gift voucher.

Do any of you have daughters this age - late 20s I think? What would they want as a thank you gift that is appropriate to receive from someone in a work situation?

https://www.lottieshaws.co.uk/a-great-big-thank-you-hamper/

These look lovely and only £33 incl.delivery and free card. Lots of the reviews mention them being given as professional or work gifts and very well received. I would say they're treat-like but not over-the-top embarrassing level. It's a lot for one person but can always be shared with friends/colleagues/packed lunches/days out. My twenty-something DC would love to receive one of these!

For someone in their late 20's? Who quite possibly lives in a flat?

I like the idea of a lovely notebook and pen.

Or a voucher for local nice cafe/coffee shop.