The third of the third today. Mad March: the month that exposes the north-south split. When temperatures in the south of the UK will likely be a few degrees warmer than in, say, Scotland.
Southerners may start to take risks with planting and sowing that would be inadvisable further north. That said, first-early potatoes should be good to go into ground most anywhere by the end of the month. Just keep an eye on your most-trusted local forecast.