Nigel, You are correct 900mhz is used by Vodaphone so it would be illegal to even switch one on within the British Isles. However, the 2.4mhz is legal but not at the power output of 130mW is 30mW above the maximum power output permitted, so is also illegal but no one appears to be making a noise about it... The UK regulator is OFCOM but they are probably in discussion with DJI to reduce the output power or at least build in restriction so if you connect in the UK it is dropped to 100mW.
However, as it is illegal to fly beyond the line of sight, higher than 400ft or more than 500m horizontally away from the pilot then reducing the power would not affect those in the UK who fly legally.
As for wanting to fly further and further afield is very dangerous and will eventually end in tears when someone gets hurt or worse.