Generally, armed Brits haven’t spent that much time roaming the area of what is now the Czech Republic, but we have spent some time there.
For instance, we didn’t get officially involved in the Thirty Years War that ravaged central Europe for, well, about thirty years, but plenty of Brits did get involved on a semi-official level with some government support. For example, in 1620 a Scot, Sir Andrew Gray, started raising a regiment in London and Scotland to fight with the Bohemian-Moravian army. He ended up with ten companies, including 2,500 musketeers. They then headed for Bohemia to fight off the advancing Imperial and Bavarian troops, not, unfortunately for them, with huge success. They lost a lot of men, and Gray’s regiment consisted of only 300 troops by the time they left and headed for Upper Palatinate. During the Second World War, we spent quite a lot of time bombing targets in occupied Czech territory linked to the German war effort, such as the Škoda works near Plzen. SOE also dispatched many missions to the area. Chicheley Hall (in Buckinghamshire) was SOE’s Special Training School No. 46 and was used from 1942 to 1943 to train Czechoslovaks. The most well known of SOE’s Czech operations was the assassination of Reinhard Heydrich in Prague in 1942 during Operation Anthropoid. After the killing, the Nazis murdered many and conducted the notorious massacre at Lidice.