In particular, did they fight in the territories of modern-day Belarus or Lithuania?

**Update**: Online sources (<https://en.wikipedia.org/wiki/Allied_intervention_in_the_Russian_Civil_War#Caucasus>, <http://www.nationalarchives.gov.uk/pathways/firstworldwar/spotlights/allies.htm>, <https://www.historyanswers.co.uk/history-of-war/saving-the-war-or-killing-bolshevism-in-the-cradle/>, etc) state that troops were deployed in **North Russia**, the **Caucasus** and **Siberia**. Furthermore there was a British naval force in the **Baltic** as mentioned by @JohnDallman.

However, I've not yet found clear sources indicating the precise actions and movements of British forces (which are typically described as 'muddled and half-hearted'), and in particular, whether the British presence ever extended to the **Southern Front**.