I suspect that on the issue of the product name, the problem is not so much about copyright as with Trade Marks. I suggest you go to the UK Intellectual Property Office website
and using the search facility see if the name of the product is a registered trade mark, as seems highly likely. It is also possible that the film company has registered the film title as a trade mark. Note which classes any identical or nearly identical names are registered in (this will obviously include foodstuffs, but may also include other subject matter). If you feel there is any overlap between the activities of your film company and the subject areas in which the trade mark is registered, you may have problems, especially if the film title has been registered too.
As for whether the film title itself has any copyright protection, this will depend a lot on the actual words involved and how distinctive they are. For instance "Quantum of Solace"* is very distinctive and unlikely to crop up other than in the context of that film and therefore would be more likely to attract copyright than would a title like "Summer Holiday". Generally speaking in UK caselaw names and short sentences made up of commonplace words will not attract copyright because they do not display much creativity or originality. If you feel there may be a problem with the specific title you would like to use it might be worth consulting the copyright owners (probably the director, producer and script writer or a company set up in their names) to see if you could license its use.
As for using silhouettes of two of the characters in your logo, under UK copyright law I beleive you have quite a bit of freedom. This is less the case in the US where the courts seem to take a broad view of the protection of characters, using the argument that a character is the expression of an idea (the story of the film), and so since a silhouette is a copy of something which attracts copyright, it would infringe. As I say I don't think that currently, the UK courts take such an extreme view and would be looking to see if there was a more straightforward copying of, say an actual frame of the film or a close parallel to the screenplay. Again the more distinctive and unmistakeable the image you want to copy, the greater the danger of infringing. For example a silhouette of a Sherlock Holmes type of figure is fairly generic and does not immediately lead anyone back to a specific Holmes film from a specific film company, whereas the silhouette of James Bond used in the opening credits of the earlier Salzman-Broccoli films would be specific to that particular franchise even though there are dozens of individual Bond films. You might also need to check that there was no trade mark registered for the silhouette you wanted to use, although if it was registered in the 1980s, it might now have lapsed as registrations need to be renewed every10 years.
* Incidently, Quantum of Solace is a registered trade mark in wide range of classes.