As a true Brahmin, kindly do the anushtanams and tharpanams where ever you are.
If you know the mandiras, you can do tharpanams anywhere in the world. Even other wise many you tube versions/online sources are available to practice them. In fact a brahmin must be well versed with Sanskrit and must say the mandiras all by himself. Acharya's are for others only. Nothing wrong in it. But Not doing it is not right.
Our smriti, makes it clear and gives the freedom that depending upon the so called deśa-kāla-pātra. (According to time, atmosphere, and the performer,) there may be little difference and we can adopt accordingly. But real purpose of dharma is to surrender to God and try to love Him. That is religion.
Earlier period, time was an issue and it takes more than 24 hours for a person to cross an ocean. He can not practice his daily routines for many many days and hence crossing an ocean was forbidden. Now it is not so We can fly anywhere with in 24 hours. So long you get the cooperation from your family you can be a brahmin anywhere in the world. Please do not feel bad Do your designated karmas wherever you are without fail. God be with you.
If all our religious setup needs Dollars and Pounds, saying that only if we do karmas in INDIA it is worthy is nonsense.
They have already started to provide and help our Hindus to practice their karmas any where in the world. Hence please be a Hindu (Brahmin) where ever you are.