Not yet here in Derbyshire, but with this warm spell it wouldn't surprise me if they're early. They normally arrive during the first week in May & I usually put a celebratory thread on here. :o)
Friend who is a market gardener spotted two birds last Sunday. He only caught a glimpse, so he's unsure whether they were swallows or house martins. Either way, they're nearly a month early here, just north of Dundee.
Mine come back every year to the same stable and have about 2/3 lots of young. There is only 1 though!! and it has been here in South Yorkshire about 2 weeks.