Perhaps starting small is the best plan. It will be some time before she can clap her hands together and bring on a thunderstorm, or turn a boy into a hawk or fish, but there are things she can try. Small magic, hedge and hearth-craft. The 'low' magic she can remember him scorning, leaving to wisewomen and charlatans once he left the woods behind. Magic for midwives and superstitious peasants, not for Kings.
Sapa will be easy enough to find, just warm grape juice; she could use oxymel, she supposes, but her stomach flips at some old memory of choking down the honey-salt-vinegar concoction, so sapa it is. Chervil, likewise, is hardly exotic. Where she's meant to get papaver rhoeas, cicely or lemon balm...
(Never mind the things she's thinking of if this works; henbane, mandrake, monkshod... A diamond dissolved in goat's blood will, she fears, be quite impossible)
Perhaps it's working some magic already, even before she's gathered her reagents and made the concoction; the act of making the list seems to clarify her thoughts a little, to pull her back from wandering in dreams, so she looks more stable than she has since Elaine cast her spell, her coat drawn around her for the first time in ages – stable, or else old, the conversation with Arthur having left her with a keen sense of exactly how much more ancient she is than her appearance would indicate, the chill of winter finally settling in her bones. That she's ended up sat at the lakeside doesn't exactly argue stability either.