Green display, +/− heating (often 330 / 500 / 800)
If it looks like a Worcester Greenstar i, use that how-to.
8000 Life round white buttons
Same fascia as Worcester Greenstar 8000 Life.
8000 Style black glass round control
Same fascia as Worcester Greenstar 8000 Style.
Two grey knobs (Baxi-style)
Some British Gas boilers are Baxi underneath. Use the Baxi Duo-tec how-to if the knobs match.
If none of these match, look the model up on Boiler Manuals.
When the flow is set, go back to the Boiler Optimiser to log what it was and what you set.