They are called urinalysis strips. You can get them easily from Amazon. Or maybe from your chemist. There are lots of different makes, the best make is Siemens, but they also cost more. When you test your own wee, you compare the test strip to the boxes on the side of the plastic tub. The most important ones are leucocytes, nitrites and protein. Leucocytes show up inflammation, (if this is the only sign and is only very faintly pink after 2 minutes then drink lots of water for a day then test it again). Nitrites and protein, either or both, show up infections. Blood can also indicate infections but women quite often can have blood depending on monthly cycle
I test my own wee and if an infection shows up I take a sample to the doctors (you shouldn’t need to wait for an appointment to have wee tested) as they firstly need to check that you are right, and secondly send the sample off to the lab to be certain which antibiotic is best. If you always have a spare specimen pot it’s easily done. I have a strong antibiotic on my repeat prescription list which means that as soon as I’ve done a sample for the GP I can start the treatment. I test it a lot more often than I have infections, I suppose having the ability to test can make you a little paranoid, but once tested I can relax again. I don’t actually get many infections these days (touch wood and D-Mannose), but doing ISC means there is always the chance of one.
The only other thing I would suggest is that you make sure you keep your strips dry, maybe don’t keep them in the bathroom as, even though they’re in a plastic tub with a silicon sachet to absorb moisture, over time they can become a tiny bit damp and then discoloured so are no use. I keep a few in a tub in the bathroom and the majority in a kitchen drawer.