Is it permissible to perform tayammum and pray when pressed for time at work, or is it better to combine prayers upon returning home?

What the questioner mentioned about not having enough time for ablution (wudu') is unlikely. She can perform ablution in the restroom inside her workplace, which does not take a long time. If that is not possible, she can go to work already having performed ablution. Tayammum (dry ablution) is not sufficient, and prayer performed with it is invalid except for someone with a valid excuse, which the questioner does not have. She must exert effort to perform ablution before the prayer's time expires.

The employer does not have the right to prevent an employee from having enough time for purification and prayer. Assuming the employer does not allow leaving for ablution and prayer, please refer to Fatwa: 94340, "Ruling on work that necessitates delaying prayer beyond its prescribed time."

Delaying prayers and combining them with the 'Isha prayer is not permissible.