If you're looking to buy something specific - you could borrow £5,000 on a credit card to do it. In fact, with a 0% purchase credit card, you could then spread the cost of this interest-free.
Even if you just need the money paid straight into your bank account, this is possible with a money transfer credit card, although there will usually be a fee attached.
Credit cards let you pay back your loan far more flexibly than a personal loan - with a low monthly minimum repayment and any amount over that allowed. You can even flex the amount you pay back each month.
If you pay back the full loan within the 0% period, you’ll save a packet on interest. However, if you still owe money at the end of the introductory period, you’ll be switched to an expensive APR, which will cost you a lot more. You may be able to switch to another 0% deal, but this isn’t guaranteed, so you should set your repayments to clear the whole debt before the 0% period ends.
You will need a good credit score to take out the best cards, including 0% offers, and you usually won't know your credit limit until after you've been accepted for a card.
Missing payments or defaulting on your debt will result in a lower credit score and potentially county court judgements against you or even bankruptcy.