(Reuters) - British company Northgate Plc said on Friday it would buy peer Redde Plc for about 394 million pounds in a stock deal that would create one of the country's largest vehicle rental services firms.As part of the deal, Redde shareholders will get 0.3669 new Northgate shares for each share held. That translates to 128.4 pence per share, a premium of 18% to the stock's Thursday close.Northgate, which operates in the United Kingdom, Ireland and Spain with a fleet of around 100,000..