Condition in future
English does not use the future tense in a conditional, even if the condition occurs in the future. The present is used instead. So:
CORRECT: If I get the visa I will go to the UK
INCORRECT: If I will get the visa I will go to the UK.
and
CORRECT:I will go to the UK if I get the visa.
The negative forces us to include a "do", so the correct version of your sentence is:
Can the period be changed if I do not get the visa in time?