If I lose my incapacity benefit will I lose my DLA too?

The Atos assessment is for ESA. You're on IcB and the assessment will look at whether you should be exempt from work, be put on ESA or invited to apply for JSA. Your DLA claim is totally separate and won't be looked at at this time (although all DLA claims will be reassessed in the next few years).

Basically, Atos looks at your ability to work. DLA is about your NEEDS (irrespective of whether you work or not).

The DWP do sometimes use the evidence collected for one benefit, for reassessing eligibility for another. So, I think it is more important than ever that you do what you can to ensure that the evidence that is collected and presented by ATOS is accurate. A welfare rights specialist (such as the CAB often work with) might therefore be very helpful to you, as might your own GP/consultants.

You might also feel up to learning how to best-represent yourself, and also whether ATOS are in fact entitled to assess you (some people are exempt). Many perceive the guides available at this website very good indeed

http://www.benefitsandwork.co.uk/

Good luck!

It's not definite, you will have to inform them of the change in your circumstances just to cover your butt, in case they decide a couple of years from now that you should have told them and say they want all the money back, but you can work and still get dla, so it's not by any means a foregone conclusion.

Your DLA will not be affected in any way if lose your incapacity benefit - so you don't have to worry about your DLA