Hi Sebastian,
Thanks a gain for your prompt response, I did follow your advice and going the  way of lesser resistance, I simply use used
conda install pytorch torchvision -c pytorch
, which you recommended. The installation was successful, but when I tried torch.cuda.current_device() I got a warning
anaconda3/lib/python3.6/site-packages/torch/cuda/init.py:117: UserWarning: **
**    Found GPU0 GeForce GT 550M which is of cuda capability 2.1.
**    PyTorch no longer supports this GPU because it is too old.**
When I tried to run a python script, it ended with
RuntimeError: cuDNN error: CUDNN_STATUS_ARCH_MISMATCH
I found out that CUDNN doesn’t support 2.1 Cards. May be it uses buit-in info to determine support and 2.1 is an “official” version for GT 550M, but the fact is installation with Cuda 8.0 was succesful, and as I mentioned I even can install use Cuda 9.
It looks PyTorch has some sort of mess with versions. I think even if I manage to install pytorch from sources and link it with separate installation of cuda 9, it will still be failing in CUDNN when checking the card support. I’ll try to contact PyTorch support for clarifications
Many thanks for your help