another question is how can i even trade USD - GBP ore EUR - GBP on exchange ?
it does not allow me to deposit GBP as currency
is there another way to change currency to currency on exchange ?
Does your local bank not allow that?
This may be too personal a question, why would you want a BTC/GBP pair if you're this complicated? It should be noted that too many exchange processes are also costly. I think you can simply trade BTC with your local currency on the local exchange.