£19 for half a head of highlights, a wash, cut and blow dry, plus a Redken treatment worth £75 at TCs Hair and Beauty – save 75%Need to know: Save 75% on half a head of highlights; includes a wash, cut and blow dry; Your tresses will be nourished with a Redken treatment; What & why: Katie Perry has been spotted sporting a blue hairdo this February, which we reckon must be testament to how she’s feeling. But if you don’t fancy dying your tresses a shade of indigo, and are fed up of feeling blue,…