Trying to start a business becoming a marathon, help needed please?

First post!

Hallo to all who read my first post.

To give a little scope on what I am trying to achieve here in Germany I'll start with a little background of myself and i'll try not to confuse you, the audience.

I moved to Germany in late 2019 in a rush attempt to get ahead of the Brexit bulls***, because let's be honest... that's all it is, or was I suppose. I have always dreamed of moving here because of how beautiful and peaceful of a country Germany is, not forgetting its great infrastructure, booming economy and most of all, my huge love for all things motorised.

Before I left the UK, I worked as a self employed freelancer for multiple companies throughout the north west UK in automotive engineering covering many areas including but not subject to, advanced diagnostics, electrical, mechanical, programming, coding, software development, including performance enhancing modifications and ECU/TCU remapping. I have worked in this industry for 10+ years and have only increased my knowledge base when progressing into other areas. I have never had a single issue with self employment in the UK due to the laws being very different to the Master Craft or Meister's laws here in Germany.

SO.... here in lies my problem. I have come this far in the industry and not a single qualification to show for it (other than accreditation's by diagnostics and specialist parts companies.) which happens to be a massive problem in Germany, something i only found out after I put my feet solidly on Deutschland soil.

Now, I have spoke to multiple municipals, councils, insurance companies, legal cover providers, local businesses in the industry and even the accountancy firm that works for my partners business in Germany. Most say there is a way and I know that maybe the case because I have met German locals that own and work in automotive trades without a Meister but, it gets hazy from there.

I have even spent time with local businesses, consulting them on things that they are having problems with vehicle related. Some of them have offered to employ me full time because of my capabilities after just advising, also because of the rare and expensive equipment i posses, along with them being able to offer other services based on my skill set and equipment. It is no offence to them and I fully appreciate any roles or jobs offered to me but I want to make my own mark, I thoroughly enjoy working for myself and it has just become a way of life now.

I currently have no employment of current because I am devoting all of my time to trying to secure myself a place here in Germany by means of self employment and starting a business in the motor trade.

I have been told to offer a Renn Service or work in the Motorsport industry, this just's means i can not work on all vehicles which would single out a massive market for me. I would also like to only work for trade as I used to get a lot of work from local trade alone. It has also been a long time since I have dealt with the public or end consumer (which suits me perfectly because its works out as less hassle this way, no offence to anyone but I'm a fussy end consumer and i wouldn't like to deal with myself either...) but this may change in time.

A long story which is my current headache, in short... Can someone please help?

I'm not sure what help one could offer. Nobody can simplify the rules or situation. I think it is realistic to think that such a move is going to cost something and not necessarily be the optimal dream one might think of. Many people would love to be in your position and have an offer of a job. Wouldn't it be more secure to take such an offer and hold off on self-employment until you have more information, more networking contacts, have become more understanding of the business culture and language?  Say give it 3 - 5 years and then if you still think it is doable you will at least be better informed and ready to make a go of it.

Although your description of what you want todo seems hazy, I assume you want to start a car mechanics business (or a kind of glorified version of it).
If this is a profession with "Meisterzwang" (compulsory to have a "Meister") - you should clarify this with the relevant authority! -  then you can only do such a business if you are a "Meister" or employ one. There is no (legal) way around it.
Also, starting a business in Germany is complicated, costly and time-consuming. To fulfill all the registration, licensing, taxation, accountancy, etc. rules (which are invariably in buerocratic German, which is a challenge even for native speakers to digest), you basically need to engage professional assistance (for a fee), such as a startup consultant, accountant, tax adviser, lawyer.
And given the difficult market (full of cheap Eastern European competitors) and fickle customers, both of which you do not yet understand, I can only second Tom's suggestion above to start with the offered job (and much less headache), test the waters for some time and develop your business plan once you know what you want to do and how.