The StormGrid radar has more than thirty controls. This page explains all of them: what each layer shows, when it is worth turning on, and whether it needs a free account or a subscription.
The rain itself and how it is drawn — colour scheme, smoothing, opacity and base map — plus the whole animation, radar coverage, borders and place names. The safety layers are open to everyone too: Met Office thunderstorm warning areas, Environment Agency flood warnings, and real lightning strikes. Anything that answers whether it is raining, whether it is about to, or whether you are in danger stays free.
Rain accumulation totals, the current-weather overlay, tapping the map for conditions at an exact point, and UK air quality. There is nothing to pay for these.
Precipitation type, Environment Agency rain gauges, road and motorway risk, windstream, the world storm tracker, fire detections, weather stations, and the five-minute European radar feed. Pro + Charts adds the EUMETSAT satellite layer.
Every real limitation is written next to the feature rather than left to be discovered later: smoothing only applies above a certain zoom, flood warnings and rain gauges cover England only, road risk is a derived advisory rather than an official warning, and the predictive nowcast has no data feed behind it yet.