little help with a leg injury?

[i'm "fein"]

Numbness is related to your nerves, could be over stretched, compressed, but really it's hard to give you an answer that based on what you wrote or without actually assessing you in person.

As far as seeing a Physio on the NHS is concerned, you need to visit a GP who will refer you on. Both physio on the NHS and your NHS GP will be free.
The only downside, is that as your complaint doesn't seem to be too bad, you might have a quite a wait on the NHS, as they prioritise based on severity. As the waiting lists are pretty long, you might be kept waiting a while.

Hope this helps