http://en.wikipedia.org/wiki/British_Sign_Language

Don't usually use wikipedia for reference however it did give some useful idea's for who might use sign language (inclusive of deaf people) as well as some information to do with qualifications:

British Sign Language can be learnt throughout the UK and three examination systems exist. Courses are provided by community colleges, local centres for deaf people and private organisations. Most tutors are native users of sign language and hold a relevant teaching qualification.

Signature excellence in communication with deaf people is accredited by the Qualifications and Curriculum Authority (QCA) and provides awards at the following levels:

• Level I – Elementary
• Level II – Intermediate
• Level III/ NVQ 3 – Advanced
• NVQ Level 6 – Required as part of the NVQ Level 6 BSL/English Interpreting. (This qualification was formerly called NVQ Level 4)

The British Deaf Association has formed the BSL Academy to provide an official British Sign Language curriculum and tutor training.

In Scotland, there is a Scottish Qualifications Authority (SQA) system for students learning British Sign Language. Currently there are 3 levels in the SQA system (continuing assessments):

• SQA: Introduction to British Sign Language
• SQA: British Sign Language Level 1
• SQA: British Sign Language Level 2

There was also this image:

I like that they've pulled out the vowels together however I think it's strange that the letters are larger than the actual diagrams...