I currently have a Schengen visa and work in Sweden. I have a job offer to evaluate in the UK. Is it possible for me to ask for a temporary permit from Sweden to work in UK? Or do I have to look at applying for a fresh new visa altogether?
Sweden cannot authorize you to work in the UK (except by giving you Swedish citizenship, but let's assume that to be beyond the scope of your question).
To work in the UK, you will have to apply for an appropriate visa from the UK. You can submit the application for this visa in Sweden, but the application will be made to UK authorities.
A good place to start might be the UK government's page Work in the UK.