The best type of loan for a startup is one that can be made without any personal guarantees being given. Look for convertible options that accept the higher level of risk in return for a small equity stake in your business if/when it takes off....

If the business is viable then an overdraft on the business current account will provide a flexible facility to support a shortage of cash. Note that the bank may require a track record to grant this and will often ask for personal guarantees....