Scrying and healing meditations can be done by gazing into the reflective surface of the water. For those with some money available and a taste for something unusual, small fountains of rough natural stone can sometimes be found in garden shops. The initial cost may be a few hundred dollars, but a fountain pump runs on less electricity than it takes to run a fish tank air purifier. The musical sound of moving water can deepen meditation and provide a refuge from the distraction of everyday activities. If you are not fortunate enough to live close to a river or waterfall, this might be a useful alternative.
Inspiration is one of the roots of Celtic worship.
No scripted rites are necessary for the worship of Celtic Goddesses. Poetry is their preferred form of invocation. Time spent in an herb garden or among the wildflowers could easily inspire you, as it has many poets over the centuries. Even if you are not feeling particularly inspired, there are a number of books available with samples of Celtic poetry that can be used or modified for your rituals. Other folk poems use herbs and plants as a part of their symbolism, even if they are not directly related to the use and cultivation of healing plants.