Just to answer this question properly:
In short, there are senior civil servants who run things on the basis of 'no changes'. So, they sign off on things needed to keep the previous state of affairs in place, but they don't do anything 'new' unless they're directed to do so by Parliament. If you look at Northern Ireland right now, this is how things are done: the civil servants implement the decisions made by the previous NI Executive.
So even if there's no functioning government, it doesn't really matter very much.
Yes, I’m aware that the civil service can continue to run the day to day running of the country (like they normally do). Ministers are there to set policy. A lack of anyone to change policy for a short term is not a problem. However, if events mean a policy decision is needed, that’s when there could be difficulties.
So with Northern Ireland previously, the various department budgets could not be increased, causing a gradual worsening of some services as inflation reduced the amount that the existing budget could buy.
With inflation approaching 10% and still increasing…
And currently reports are that Boris does not want to step down as PM until just before the Conservative party conference. That’s a fair chunk of time.
Although there are also advantages in their being a lack of ministers, as in most of the controversial laws are very unlikely to be passed.