It’s hard to answer your question because it’s difficult to determine what you mean by “at fault”. At fault for what?
Assuming, hypothetically, that an accident occurred because of this, then if the cyclist were to continue on the road, and the vehicle collided with the bicycle, then
The Highway Code’s hierarchy of road uses (with pedestrians and cyclists being at the top of the priority “food chain”) would more than likely mean that vehicle would be expected to observe the presence of the cyclist in the context of the layout of the road and potential hazards, and anticipate any potential danger and adjust their driving to accommodate for the safety of the cyclist.
However, if an accident occurs then it’s important to remember that (in quite a lot of cases) that fault doesn’t always lie completely with one party or the other. If the cyclist didn’t take care of their own safety (not looking, etc) they may be “contributory negligent” and could share a proportion of the blame.
If it were the case that the cyclist goes on to the pavement and injured a pedestrian, then I could easily see the cyclist being at fault.
There would be several arguments made that it wasn’t an absolute necessity for the cyclist to go on the pavement, and should have judged the situation and perhaps stopped until it was safe to continue on the road. (Ie, why would the pedestrian be at fault?)