Britain's first bank-financed biomass plant for 12 years is set to get the goahead after a three-year struggle to raise the cash.  David Williams, chief executive of Eco2, the company behind the plant, which burns straw to make electricity, told The Times that the tortuous process underlined how scarce credit was for biomass developers.  Royal Bank of Scotland, UniCredit, Siemens Financial Services and NIBC are expected to sign off in the next fortnight on ?120 million of financing to build the Lincolnshire plant, although completion could be delayed again.  The 40MW plant, which will be large enough to supply power to 40,000 homes, was given planning permission in November 2008. But with the onset of the credit crunch and uncertainty and delays over government subsidie