Just my opinion, but I do think in the next 5-10 years there will be a "cyber war" and a heightened "trade war".
We are already in the midst of a trade war and I see this becoming far, far worse with Taiwan, Middle East and NATO/Russia conflicts. Britain needs to start becoming more self reliant, especially after Brexit, otherwise costs will remain extremely high and we will have absolutely no quality of life for the next lot of decades.
I can see a cyber war starting in the next 2-5 years, with attacks on our cyber infrastructure, spyware, power grids being attacked, satellites etc. This will have an impact on our technology and national security. They will do this first before feet on the ground as in this day and age, attack on security systems, cyber etc is needed for a successful invasion.
As with invasions/feet on ground/physical war. I could see this coming to a head in the next 10 years. I don't, however, believe that the war will take place physically in the UK, but other parts of Eastern Europe, Scandinavian countries, Asian continents and Middle East. I believe that it will be a NATO vs the others battle. It will probably be the longest war in history as so many countries will be at play across the world. During this time, conscription will likely be introduced again, multiple terrorist attacks in UK, ban on travel (due to attacks and also cyber war). We will be confined to our own countries and the economy will completely collapse, leading way to a world currency/bank in the end governed by one powerful entity (I see this being a mix of all powerful leaders from each continent) as it will be determined that no side can actually "win" without nuclear war and destroying the entire planet.
I would say this wont be for another century or so, with conflict lasting 80+ years between powerful nations, with multiple wars in different parts of the world.
We see it panning out now.