I think switching to TT earth is probably the best and safest option, so thanks for helping me reach that conclusion. I was initially not so keen given it is hard to get anywhere near the quality of earth connection that you can from DNO TN-S…
Only follow on question I guess is what I can do v.s. needing an electrician for. Installing an earth rod and running the cable to consumer unit is entirely doable, but then I guess definiing a new MET and disconnecting DNO earth is something an electrician would need to do…