I don't believe UK is shit at all, in fact it's rather good here and personally, I love the UK.
However, I can believe for some people life is a bit shit at the moment, especially if you are struggling with the cost of living, job prospects, partner problems, elderly care or any number of other 'life' problems that would have hit you anywhere.
Secondly, I do think that some people have a very negative mindset and this is pandered to by the press/media. Whatever the public is given, there are complaints, it isn't "good enough" or the press pulls holes in every political party/decision/attempt to change things before they've even been given a chance.
Thirdly, there are vast areas of the world where life really, REALLY is shit - these areas are full of poverty, disease, war, famine and a huge lack of resources and infrastructure. We are so lucky not to live like that in the UK, anywhere. Nor do we suffer from serious weather, hurricanes, earthquakes, volcanoes, seriously dangerous diseases....
Fourthly, some of the best nations I have lived in do not have sunny weather - try Scandinavia. Northern Norway and Sweden have winter for more months than we do; they manage perfectly well through blizzard season, happily cope with temperatures -25 for weeks on end and darkness from November to February. And do you know what, they don't complain about the weather either. Since it's not possible to change a country's weather, they've learned to embrace it instead, rather than constantly ranting about it.
Finally, the Scandinavian countries have one of the best standards of living I have experienced. Their health care is brilliant, their schools are good and rates of literacy is very high, unemployment very low. Many goods are expensive but things like energy and childcare are very cheap indeed, to make it possible for people to live. How do they pay for this? They happily accept high taxes, which goes to create such a society. In comparison, UK has a strange mindset which wants everything provided but assumes there must be some magic money tree which might pay for all this.
The "solution" you asked about could include a change in mindset in the UK, and a preparedness for everyone to work together to create the sort of society we really want.