Cash is nearly always a problem for small businesses. You agree terms with your customers and then they don’t pay you on time, so you can’t pay your suppliers on time, or can’t pay HMRC on time. This is a difficult problem, but, with certain disciplines introduced, it is manageable.
A rolling weekly or monthly cash projection can provide advance warning of when cash could be tight, but allows time to manage the problem. A much better solution than ignoring it until the bank bounce some cheques!