Hi Squidge
My wife and I struggled with Keffir to start with but now we enjoy it, it really is an acquired taste! If you make your own you can tailor the taste by fermenting it for a shorter time if that suits your tastes more, increasing the time and pungency as you get used to the flavour. The same applies to Kombucha. You can also add things to both during the secondary ferment change the flavour.
Try mixing Keffir with other things to make a smoothie-that really masks the taste. I use mixed berries, chia seeds, spinach and avocado in mine (making a pre biotic and probiotic cocktail!) but I also add other things from time to time.
Making Kombucha and Keffir really is quite easy, you will save a fortune making your own and arguably end up with a more diverse mix of microbes . I purchased both my grains and Scoby off Ebay and haven’t looked back.
Good luck!