One should never file Y or Z in the UK
The problem with Fairoaks is it shares Farnborough's standard routings. To get to near France via DVR these are a right pain routing GWC, SFD, LYD then DVR whereas I'm happy with a short VFR hop to BIG where I can join their standard route to DET-DVR and vv. IFR out of Fairoaks to Le Touquet etc adds 80nm to the route for no reason whatsoever if I'm happy with a VFR service through the "alley" to BIG.
/Y or /Z is the proper way for me to offer that flexibility yet it doesn't seem to work!