According to cover of the news in The Guardian, the initial £20 billion will "be used for the National Loan Guarantee Scheme which is intended to reduce the cost of borrowing for small businesses." In referencing the announcement, the coverage notes, "the important thing is to get credit flowing to small businesses. The National Loan Guarantee Scheme will allow banks to benefit from the government's top-notch triple A rated guarantee that, theoretically, should reduce the price they pay to borrow money on the markets -- either directly from other banks or by issuing bonds."
Here in the US, the Federal government has done a wretched job of improving the working capital and borrowing situation for growing businesses, post-2008 downturn. While SBA loans have always been available, these programs rarely address the need for revolving facilities often needed by growing businesses without specific, up-front capital or investment spending requirements. The most creative uses of small business financing in the US have come from larger procurement and AP organizations, some of whom have made it a strategic imperative to get cash in the hands (at a low APR) of key suppliers that need it the most to fund working capital growth needs (e.g., inventory, new capital investment). CAT, among others, has taken the lead here.
As a small business owner and analyst who covers the electronic invoicing and dynamic discounting market, I can honestly tell those organizations worried about their supplier's access to working capital that regardless of which side of the Atlantic that you're on -- and the new Bank of England funded program in the UK -- that supplier access to working capital should be a top concern in the current market. That is, if supply risk management is something that factors into your vendor management equation in the least.