The United Kingdom consists of England, Scotland, Wales, and Northern Ireland. Most areas, especially cities, in the United Kingdom are safe and good for solo travelers. There are relatively low violent crime rates. You can comfortably explore England's capital city, London, even though you are traveling by yourself. Moreover, cities in Scotland like Edinburgh and Glasgow are also lovely to see and explore as a solo traveler.
Solo traveling in the United Kingdom is fun, but solo travel groups can make your life easier. You can share costs, transportations, and accommodations with your new UK travel buddies, who are also traveling solo! Then, the best part of it is that you are still traveling solo, but not alone!