Hi there,
I am from Europe and know the UK system very well for applying to doctoral programs in clinical psychology as it was once something I considered myself. I am now actually going to start one in the US (as an international student). I can only comment on the UK system but you do not need the GRE to apply for these programs or any graduate programs in general. The UK doctorate for clinical psychology is a professional doctorate en par with the PsyD in the US called the ' DClinPsych' you apply through the UK Clearing House for postgraduates. As far as I know you can only select four programs. Unless, you have the right to work in the UK then you will not be offered a funded place however, you may be offered a non-funded place if you have your own funding. See this link for non-funded programs for international students:
http://www.leeds.ac.uk/chpccp/BasicInternationalFunding.html
There is also one PhD program specifically in clinical psychology that I know of in Manchester where they welcome international students. But you will not be able to practice as this is a purely research degree. See this link for more info.
http://www.manchester.ac.uk/study/p...rogrammes/list/02948/clinical-psychology-phd/
Someone mentioned that you apply to a potential adviser and that this is the first step but that is not the case for clinical psychology in the UK at least. However, if you were interested in a research only PhD in psychology then yes, you would definitely need to contact them. It is very competitive to get into the clinical programs as they are well funded and like the US, there are very few spots. It is not uncommon to do a research PhD first and then apply to the clinical programs (both are three years approx. in duration). Something to consider. It is not impossible to pursue this route in Europe in your position but you have to very outstanding in some way to have a shot as there are so many qualified applicants in Europe too. Sorry I cannot comment on Germany or any other country in Europe but the UK and Ireland are, I think, the only countries that require a doctorate to practice-which in my opinion makes them better and more respectable training programs.
Good luck!