A:
Firstly, the basic rule
is that you should perform Ghusl after a wet dream resulting in ejaculation; but if doing so would leave you diseased, then it will be permissible for you to perform Tayammum which is prescribed in cases of absence or lack of water, or the inability to use it because of a disease.Secondly, congregational Salah (Prayer) is obligatory and performing Ghusl is a prerequisite for the validity of Salah. Therefore, if water is available, you should perform Ghusl and not Tayammum in order not to miss the congregational Salah.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.