What am I looking at? I am in Northampton England and every night in the SW sky is a very bright, white light that twinkles. It visibly appears to be moving towards the west but appears pretty much the same start place every night. Could anyone possibly tell me what it might be please?
Is it moving straight to the west (i.e. it keeps the same distance from the horizon) or does it 'move with the stars'?

Have you checked an online planetarium like The Sky Live? Based on the current information, it could just be Sirius, the brightest star in the night sky, or even Venus which is currently in her Evenstar period (but planets generally don't twinkle).