A few clarifications:
Generally only one turbine will be lit on a wind farm
They are normally lit
Very few wind turbines in the UK are lit, although the proportion is now growing because the MoD now asks for lights. I know of no case where only one turbine in a wind farm is lit.
the largest wind turbine in ENGLAND today are 115m high
Pretty much the standard height now for onshore turbines is 125m. There are some currently going through the planning system at 149m.
enstrompilot: you say
I fear the constant noise and visual impact
but those of course are nothing to do with the safety of your helipad operations. I suspect downwind turbulence is probably your biggest potential issue.
NS