SHOPPERS have until April 11 to collect vouchers in Tesco’s Computers for Schools scheme. One is issued for every pound;10 spent in the company’s supermarkets. One in two schools in Britain participates in the scheme, which has provided more than 34,000 computers and more than 250,000 related items worth pound;44 million since it began in 1992. Vouchers can be donated to any participating school. For more details call 0870 010 0708 (premium rate number) or email computers_for_schools@bell-pottinger.co.uk