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?