We did this one to death on another thread about night flying not so long ago. NO IFR plan has to end in an Instrument approach. All flight at night is IFR, crossing of controlled airspace is special VFR returning to IFR at the exit from controlled airpspace if you do not hold an IR. An IMC holder is still required to get a SVFR clearance in Class A airpspace but the minimas are less. An IMC holder with a night rating can legally fly out night out of the sight of the surface and end the flight in either a visual or an instrument approach.
There have been so many rumours and legends created about this that the CAA have taken the effort in the latest GASIL to actually point out that there is NO SUCH THING as night VFR.
ANYONE can file an IFR flight plan but they need to operate in the limits of there licence. A PPL with no IMC/IR has to remain VMC in sight of the surface at all times even when operating on an IFR flight plan. IFR does not control the conditions that you fly in, just states the set of rules that you will follow. If above 3000ft you must be 1000ft above the highest object within 5nm of track etc etc etc etc.
The channel Islands is an interesting example, the zone is class A but the ATZ is actually class D so an IMC holder can fly to the Islands IFR, get a SVFR clearance accross the zone, return IFR in the Class D airspace and land on an Instrument approach all perfectly legally. The same applies at night.