You'll have severe difficulty locating any of these ancient lanterns outside Gatwick. I would strongly recommend reading the rather long colour vision thread, as it contains many details on the lantern tests, things you need to know that the CAA won't tell you when you take the test etc...
I, for example also fail a couple of the Ishihara plates. I went on to fail both the lanterns at Gatwick, by a whisker. 2 years later I passed the Spectrolux in Zurich (another approved JAR test) and I'm now unrestricted. It's a very individual thing - some pass easily, some don't. What's universal however is that the tests are all completely irrelevant bollocks. Even the CAA has admitted they are not fit for purpose.