Sursula has a point, it's difficult to give a blanket answer for a process that has a lot of individual factors influencing the outcome. I'll try to provide my own perspective anyways:
Let me preface this by stating that I am not precisely in your field (I am somewhere between environmental science and statistics) - so take my advice with a grain of salt. I have, however, recently gotten an assistant professorship in one of the aforementioned countries, so I have a bit of insight into the process.
As far as publications are concerned, from what information you provide, I think you are definitely ready to apply for such a position. Your experience with funding acquisition and teaching definitely also play greatly in your favour! Keep in mind that - contrary to popular belief - many departments (personal opinion: at least the good ones) don't care as much about the raw number of publications as much as they do about the novelty, potential, and relevance of your research. And the raw number and even venue of publications doesn't always imply these things. If you can convince the committee of your excellence with just five publications, you will beat any competitor with twenty manuscripts about mainstream, trite, or trivial research. Make sure you have a distinctive and convincing "research brand".
As far as concrete steps into a junior group leader position are concerned, remember that faculty searches unfortunately often involve a great deal of chance - there's always a lot of factors in play behind the scenes that you won't be able to anticipate, so don't take rejections too personal. Finally, I don't know about Great Britain, but for the EU, Germany, Switzerland, and Netherlands, there are a number of fantastic starting grants to fund your own junior research group. I recommend checking those out while you scan for suitable faculty searches:
For the EU, check out the ERC Starting grants (success rate is about 8%).
For Germany, check out the DFG Emmy Noether programme (success rate is about 15%)
For Switzerland, there are the SNSF Professorial Fellowships (success rate is about 20%)
For the Netherlands, I don't there is an exactly equivalent starting grant that also funds PhD students and researchers. The closest thing, I believe, is the personal Veni grant - but this one only covers your own salary, to my knowledge.
Applying to one of those, by the way, also strengthens your applications for faculty searches - an applicant who already has a finished proposal to throw onto the Roulette table often gets a bonus point =)
