Personally, if I felt strongly enough to warrant my taking any action (and it would have to be a damn sight more more than me just having a bad feeling) I would not involve local plod but would be far more inclined to report the matter directly to the security services.
They are the experts with the resources to investigate and if necessary take the appropriate action plus they are not as answerable to some jumped up civil servant who is clammering for statistics. If they feel that any action is required you can rest assured it would be taken without you having to suffer the hassle of having your every action and GAR Form scrutinised under a high-powered microscope.
There are a lot more threats to national security than high profile Islamic fundamentalist terrorists. We all seem to forget the drug and people traffickers which are far more likely to involve GA.
There are 22 blokes that need investigating at the moment for obtaining property by deception, in that they are receiving vast sums of money under the pretence that they are professional footballers!!! What a boring game!!