8-10 channels should fly almost anything with flaps and retracts and maybe droppable drop tanks or bombs. Just remember, the more channels your plane needs, the harder it will be to build and set up properly. If you're planning on flying a 4-5 channel plane to begin with, an 8 will work fine. It will also give you some "room to grow", something that is never a bad thing.
Just did a little checking on frequency bands. While the US has designated 27 and 50MHz(the later requires an FCC license), along with the 2.4 GHz band as general use and 72MHz bands for aircraft only, in the UK, it's 27Mhz and 2.4GHz for general use and 35Mhz for aircraft. Something else that won't apply to you is all of the FAA restrictions. I don't know what the UK's equivalent requires, might be something to look into as well.