Currently it is taking about two to three months for a work permit to be approved.
Most people need to apply for entry clearance to the UK prior to travelling to the UK. There is also a requirement that the spouse and dependents of the work permit holder apply for entry clearance.
Because of Security clearance procedures, applications can take longer for Russian nationals, and can take a lot longer for nationals of North Korea, Libya, Iraq, and China (PRC).
In general, entry clearance applications to the UK may take another one or two weeks after the Work Permit is issued.