Rejecting your characterization of this war entirely, there is no current risk of the UK sending troops at the moment.
However, there is the risk of escalation where Nato would get directly involved such as if war criminal Putin carries out his threats about creating a nuclear event at the Zaporizhzhia plant. If that happens, Nato might then enter because of fallout in Nato nations, and then Russian side would soon be crushed. Thus hopefully unlikely as the last thing Putin wants at this time is to directly fight Nato.