callum91:
If there is an IFR arrival under Procedural Service and an IFR departure and for example, the departure requests only a Basic Service, do they get no separation from the arriving traffic?
It only needs one of the two to be on a procedural service for separation to be applied. If the outbound chooses to be on a BS (presumably in order to avoid delays) but there's an inbound on a PS, the outbound will get no benefit because the controler will be applying vertical and/or time/distance separations to keep them clear of the inbound.
My (limited) experience of doing practice IFR approaches at an airfield outside CAS is that the ATSU insists that you remain in VMC. This enables them to, for example, release an IFR outbound and just give traffic info to both parties. Seems to work well although it can mean flying the practice approach (especially the hold join and any holds) can be a little challenging.
I find it hard to understand anyone in the approach environment asking only for a BS unless they are confident they will remain in VMC.
NS