EMDR, like all therapies, affects everyone differently and so it's impossible to know how you will feel afterwards or if social catchups will be what you need at the time. In my experience, EMDR can have a fairly profound impact for a while and can sometimes leave you feeling pretty tired, a little disorientated and in need of some down time and rest. the processing can and often does continue for a time after the session and it can take a while to get used to that feeling.
That said, I think it's also important to have some positive structure and routine to help you to become and remain grounded and to give you a break from the heavy processing of EMDR. I'm not sure of the relationship you have with your mates, or to what extent they understand what you're going through with therapy, but it might be a good idea, if possible, to let them know that you're going to be working on some fairly heavy duty therapy beforehand and you can't quite be sure how you'll be afterwards. So if you could maybe keep your plans flexible, so that you can change them to do something quieter and more low key if necessary, or even postpone for a little while if you need to rest for a while first, then this might give you the advantage of having something positive to look forward to without the pressure of having to front up and socialise straight away if you need some down time first.
EMDR has been a really positive, though challenging, experience for me that has probably taken me further through trauma processing than any other individual intervention. I wish you the best with it and hope you too have a positive experience.
Maddog
