Soft brushes shouldn't go frayed within a day or two, if they do it is a sign you are putting too much pressure on it which will damage your teeth and gums over time. This will be much worse if you use a firm toothbrush. Always use a medium bristle brush.
Floss and interdental cleaning aids are very common here in the UK, you just need to know where to look. Have u been for a checkup recently and did you have some cleaning done at the same time? If not, I would advise having a clean done asap and returning to see your dentist in any case if your gums remain sore. Flossing shouldn't be sore, your technique may need checked and your dentist can help you with this.