Got my work appraisal tomorrow, is it ok to tell my line manager about my aspergers and show him the methods I best learn or is this too negative?

Your emploer/manager/line manager should make adjustments for you if you can show your autism has a major effect on your daily life and normal activities and therefore covered by the equalities act. Showing major effect on your day to day normal activities isn't as difficult as you may think, examples are confusion caused by slow processing of information, taking questions and requests literally, sensitivity to certain sounds, smells, tastes, not enjoying social occasions, social anxiety, and many more. 

These adjustments needn't be major, for example a desk in a smaller office or a quieter area, being allowed a little quiet time and a relaxation of work targets.

If you contact access to work,  a government scheme, they will assess what adjustments could be made and can fund you a few hours a month with a support worker and some training for work managers and colleagues with your permission.

You are probably affected in more ways than you think and sooner or later this could come to a head with performance issues especially with a change of manager and different tasks.

Your assessment report should show the evidence for your diagnosis. While you would not like to show your employer the whole report, you can you may like to show extracts to show how you are affected.

There are good resources on the net, and and some of the information leaflets on the Autism West Midlands website are particularly good and showing them to your employer and discussing them may help understanding. 

But the Access to Work application is very important in my opinion.  I am a trade union representative as well as being autistic and have experience with them and would thoroughly recommend them

Your emploer/manager/line manager should make adjustments for you if you can show your autism has a major effect on your daily life and normal activities and therefore covered by the equalities act. Showing major effect on your day to day normal activities isn't as difficult as you may think, examples are confusion caused by slow processing of information, taking questions and requests literally, sensitivity to certain sounds, smells, tastes, not enjoying social occasions, social anxiety, and many more. 

These adjustments needn't be major, for example a desk in a smaller office or a quieter area, being allowed a little quiet time and a relaxation of work targets.

If you contact access to work,  a government scheme, they will assess what adjustments could be made and can fund you a few hours a month with a support worker and some training for work managers and colleagues with your permission.

You are probably affected in more ways than you think and sooner or later this could come to a head with performance issues especially with a change of manager and different tasks.

Your assessment report should show the evidence for your diagnosis. While you would not like to show your employer the whole report, you can you may like to show extracts to show how you are affected.

There are good resources on the net, and and some of the information leaflets on the Autism West Midlands website are particularly good and showing them to your employer and discussing them may help understanding. 

But the Access to Work application is very important in my opinion.  I am a trade union representative as well as being autistic and have experience with them and would thoroughly recommend them