Just checked NATS AIS website (which is the official source for UK NOTAM), the only outage is the DME "ISN" which is co-located with the 20 ILS glidepath site. If this is U/S the "SAM" DME can be substituted by aircraft wishing to fly an ILS.
The NOTAM link given (which is not NATS) refers to withdrawal of Instrument Approach procedures, which is not the case, and secondly there is no mention of ATC staff shortages or temporary closures to accommodate SRATCOH breaks. Who dreamt that one up?
Mention in quoted NOTAM of "DOD" = Department of Defense (USA)? Have they declared war on SOU and imposed an instrument approach ban?