I don't know what are legal frequencies in the UK for surface R/C but neither radio appears to be offered in 75MHz which is the legal surface frequency in the US.
Assuming you could get them in your legal frequency the first one, the one for airplanes, would work out best for you. If you have some choice regarding frequencies remember that the lower the frequency the better for submarine work. Lower frequencies penetrate the water better. Therefore, if you could, go with the 35MHz version.
Qualified in Submarines 1965
"D..n the pressure, Six-Zero feet!"
"Most men would rather die than think, Most of them do!" - Bertrand Russell
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