Yes to Cass and Ken Bromley and I'd add in Jackson's. And Arteza for the reason below. I've bought from all 4 and never had any delivery issues.
A thought - when I started back into making art I didn't want good quality stuff I wanted cheap stuff because I wanted to feel free to experiment and find out what materials suited me and what I wanted to work with. It's very, very different painting in oils, watercolours, or acrylics, for instance (and there are other choices). If you buy her oils and she discovers she wants to paint in watercolours the oils will sit around getting old and unusable. Drawing and painting, while related, are different skills and a painter might not draw much other than to discover forms and compositions to translate into paintings while a person who draws might never paint at all!
Arteza is good and while it's not one of the top-range brands/sites the quality is fine for this level of getting into it and for instance they sell large canvases much cheaper than anyone else and they are really just as good as canvases that are five times the price. Art materials is a very complex field! I'd be inclined to a voucher too, because while it's less interesting for you it's probably infinitely more valuable for her and a very exciting journey for her to have the opportunity to browse the range of what's on offer and think about where she wants to start.
If you do decide to buy something rather than a voucher make sure you know what you're doing. Different paints are used with different substrates - watercolours usually on watercolour paper, oils usually on canvas but there are other options, acrylics usually on canvas but again not exclusively. Etc etc.
Obviously I could say a lot more. I feel so passionately about art nowadays and truly wish I'd started years and years ago. You are doing a lovely thing for her. Sorry if I've given you way more info than you need your question just sparked off a LOT of thoughts! 