You have to send your scanned Education & work expereince certificates to human resources. They will apply for a work permit and nowadays it might take 6 to 8 weeks.
Once you receive your work permit then you can go the British Emabassy in your place or nearby and apply for the visa.You can get information on filling the long really long application form.

First make sure that the offer is correct considering ther financial turmoil the western world face at this point of time, i doubt they will give work visa that easily