I transitioned from software to brain science for my PhD. (Caltech has a unique program for this called Computation and Neural Systems.) Universities hire regu

I transitioned from software to brain science for my PhD. (Caltech has a unique program for this called Computation and Neural Systems.) Universities hire regular software engineers all the time for software development work. Biology labs hire full-time "build-it" guys, and computational projects with a lot of funding hire part-time and full-time software engineers too. So, to break in I recommend you look up some large brain science computation projects online and contact them. There are quite a lot of them in Europe. You may also be able to get into some fMRI projects. That said, at a university, the chances of you taking more than a supporting role without a university education is slim. So, I would recommend looking for a brain-oriented startup. If you want to do moreso biology, then I do not believe this path would be worthwhile to you. Lab assistant work does not pay much, and it is often very tedious work. Some techniques may take a year to get proficient at before your results start to make sense (as was my case). That said, biologists constantly amaze me -- they routinely make heroic efforts to find evidence for tiny advancements (as is necessary due to the limitations of our brain technology).