RE: newbie needing some help
Your website link doesn't work. There is no such place as "storacing.com."
27MHz is the "toy" R/C band in the USA. I'm not sure it's usable in the UK. Frequency allocations in the UK are different from the US, and the 27MHz band may be in wide use for purposes other than R/C over there. That would explain the interference you're getting. In fact, you may be interfering with the people trying to use their 27MHz equipment when you're trying to fly your airplane. Find out if 27MHz is legal to use in your country, and what they use 27MHz for normally. You might be interfering with an application where lives are at stake...
You can change frequencies within the 27MHz band by changing crystals, but you can't switch to the UK'S R/C band (35MHz?) by just swapping crystals. The surrounding electronics are tuned to the 27MHz band, and they will be seriously out of tune if you make such a large jump in frequency. They may not work at all, or they may work on the wrong frequency. Getting the radio gear modified will probably cost more than the entire plane.
With a little ingenuity, you can install a "regular" R/C airplane system on a legal UK frequency in the plane.