C.M.
Couldn't agree more. I think your post above is top advice. The thing that has always concerned me about pilots revieving an FIS is that they may think they're going to get a comprehensive service and, unfortunately this is not the case. Here's a quote from MATS Pt1 just to show what I mean, (I'm talking about FIS provided by an Approach unit here)........'Controllers will, subject to workload, provide pilots with information concerning collision hazards to aircraft operating in Class C,D,E,F,or G airspace when self evident information from any source indicates that a risk of collision may exist. It is accepted that this information may be incomplete and the controller cannot assume responsibility for its issuance at all times or for its accuracy.'..... I think this is particularly relevant to Gatwick, for instance, because the primary task of the guy you're speaking to is to provide intermeadiate approach to IFR inbounds so the quality of the service he can provide to FIS seeking VFR traffic will vary depending on the amount of aircraft inbound to Gatwick. The bottom line is If you're VFR rely on the lookout rather than the ATC service.
Spiney