I have been banned from driving in the UK, but my job is taking me into Europe am I am taking a driving test in my new country of residence. If I return home to visit during the term of my UK ban, will I be able to drive on my new European licence?

Unfortunately, your non UK licence will not be valid in the UK whilst the driving ban is in effect.  The ban overrules any entitlement that you may have to drive as a “visitor”.

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.