Ok, but I could I ask what feels like simple question:
Elvington doesn't have a aerodrome ICAO code so the only way to find that NOTAM is to look under EGTT FIR & read through all of the posts? (I'm asking to see if there is a better way)
Not quite accurate. Nowt to do with whether or not it has an ICAO code, everything to do with whether the aerodrome information in the AIP is accurate or not. Unlicensed a/d do not have entries in the AIP and so you won't see a/d NOTAM for them, even if they have an ICAO code (Popham EGHP, Lee on Solent EGHF and North Weald EGSX are all examples). The numbers will increase as a/d drop out of being licensed now they no longer have to be for training but retain their ICAO indicators.
What you will get is a Nav Warning. The Q Line for the Elvington NOTAM was
Q) EGTT/QWALW/IV/M/W/000/050/5355N00058W003
This is what is used to select whether or not it appears in your brief. Here's the decode
EGTT - the FIR
QWALW - QWA=Air Display LW=Will Take Place
IV - of interest to IFR and VFR
M - Miscellaneous NOTAM
W - Nav Warning
000/050 - affects surface to FL050
5355N00058W - co-ordinates of the centre of the activity
003 - Radius of Influence in nm from the centre
So - if you take a Narrow Route Brief from the AIS site it will use the route width you choose to define a corridor within which your flight will take place. If the circle describing the RoI intersects that corridor the NOTAM will appear in your brief.
Simples!