Is it permissible for me to enter Mecca with the intention of performing hajj and then don the ihram clothes inside Mecca? I fear that I will be prevented from entering Mecca because I could not obtain a hajj permit. What is the expiation in this case?

If the case is as mentioned in the question, it is legally established that whoever has a reason for committing any of the things that are unlawful during the state of ihram – other than intercourse – such as shaving the hair, wearing sewn garments, and so forth, must do one of the following:
- slaughter a sheep;
- feed six poor persons by giving half a sa’ of food in charity to each;
- fast three days.

Hajj is not invalidated by committing an act specifically forbidden during ihram, except for intercourse. It was related from ‘Abd al-Rahman Ibn Abi Leila, from Ka‘ab Ibn ‘Ujrah that the Prophet (peace and blessings be upon him) passed by him during the year of Hudaybiyyah, while making hajj .
The Prophet (peace and blessings be upon him) asked him, “Do these pests annoy your head?"

“Yes," he replied.

The Prophet (peace and blessings be upon him) said, “Shave your head and then sacrifice a sheep, fast three days, or give three sa‘ of dates to six of the poor."

And God Almighty knows best.