Your best bet might be to apply to seed accelerators for that amount of money. £20,000 seems an odd amount of money to want to raise, accountancy and legal fees

Your best bet might be to apply to seed accelerators for that amount of money. £20,000 seems an odd amount of money to want to raise, accountancy and legal fees will probably eat up a decent chunk of that, if you're going after angels it might be easier to raise a large amount. What's your plan for spending that money? How far developed are you products and what markets are you working in? - if you're in the b2b space another option might be to approach potential customers and see if they're willing to finance you (or even if they can provide an letter of intent saying they intend to buy your product; you may be able to use that to get a bank loan). Another option could be to become a contractor for a while, 20k isn't a huge amount of money, you could easily earn that much money in 3-6 months (if you take payment through your company and re-invest it in your startup products it also means you won't have to pay any tax on it).