Not sure about UK specific resources, check with Garcia or MSLarsen they might know. Also you can Google the terms PH Test Strips and find instructions on how to make your own.
The important thing is to test several times a day, as you're testing saliva and it changes.
I didn't bother with testing, I just ate a diet that I knew was very alkaline and balancing. I got a juicer and started juicing
veggies like crazy. That, good oils, CalMagFizz, no meat or dairy except for eggs, and taking in apple cider vinegar occasionally will ensure that you're giving your body everything it needs to easily maintain proper blood pH so that it never has to scavenge.