My original calculation of charges to Alliance & Leicester in May was £4982.50 + interest. I am now tonight about to complete MCOL form [eek!

I'm getting nervous now] and want to know if I can alter the value of my original claim when completing the form or does it have to match perfectly with previous correspondence to A & L?
This is due to the fact we have had further charges on our account since May and also I originally included the £5 monthly interest charge in my claim, which I have since realised you cannot include.
Also, we are on holiday for one week in August. Is it best to mention this on the court form somewhere in case they set a hearing date and if so where on the form?
All help very much appreciated.