It is compulsary to have one if you live in Germany, but the public system is closed for new entrands above 55 years old. If you manage to enter (e.g. if you lived in Germany before and were member of it, or if you are member of a public health insurance system in your home country and can get a transfer) it would cost you around 290/month and .
Hm is it that bad? I had interrupted my insurance (at techniker krankenkasse) a few times using a number of tricks. of course i am younger.
Firstly, i would hope, the state system does supports moving to Germany if you are 'coming from' a similar national health system, especially EU.
Second, I am not even sure, how you would be forced to have a German health insurance in practice - you just act like you are 'for some time' in Germany (ask british NI for a EU wide paper/card). With no visa and passport stamps, and a house in UK I am not sure how legally distinguish whether you spend less than 6 month a year in Germany. Wait, if you go tot the doctor a lot, during the whole year, that might be a giveaway. But it should not matter for the first six months?
I am in a similar sitution: gradually moving out of the country, I have a natinal health insurance from a different eu country, but had a few months living in Germany, and could be there now.
As far as I know I would just go to the doctor and at the end my insurance would pay - perhaps it does not work in praxis if I would do it too often though! (I never do, actually).
First things first: call a few of them, say Techniker Krankenkasse (try to tell them before that you need an english speaker).
But be aware that the details of the regulations are complex, and the person you speak to may be wrong in the details.
Ask the same questions to different persons and try to get a feeling who is giving the right answer (since you will quickly become the best specialist for your own case)
So, before you make the final decision on a step, it may be worth communicating in writing, in case there is a lot of money on the stake!
I would have thought, it is a problem getting OUT of the British system, i.e. convincing them to not substract the money from your pensions.
I could imagine, berlin is cheaper than your present location (letting a house in the UK and rent a flat in berlin), so that a few 100 euro per month more for health insurance does not matter?
My estimate for a reasonable 60 sqm flat is somewhere between 600 and 800 euros all-inclusive, of course, more expensive is o problem. (mine in prenzlauer berg has 65sqm, balkon, and costs ca. 650 including everything) Oh, and I may move away...