I have served my disqualification period but the DVLA have not yet returned my driving licence. Is it safe to drive now?

Although your suspension may be completed, you are required to be in possession of a driving licence, so strictly speaking you should obtain same before you commence driving again. There may be various reasons why the licence has not been returned to include payment of a fee or taking a further test. You should make enquiries with the DVLA immediately to establish why the licence has been retained. You can then rectify any issues that require attention. This is the most prudent approach, given that if for any reason you are asked to produce a licence but are unable to do so, it is you that will be summonsed, not the DVLA.