The Madaaris here in the UK are saying that it is not necessary to fast two days in Muharram because the Jews are no longer fasting on the 10th Muharr

Answer

Their claim is baatil.The madaaris are astray. They have deviated from the Sunnah. They are being influenced by shaitaan, hence they seek to cancel the fourteen century Sunnah practice of fasting two days in Muharram. Instead of encouraging Muslims to uphold the Sunnah, they deviate into baatil and discourage an act of ibaadat. In fact, it is Mustahab to fast the first 10 days of Muharram.

Their argument holds no validity. Rasulullah's Sunnah may not be eliminated simply because the Jews no longer fast on the 10th Muharram. In fact, orthodox Jews still adhere to their religious practices.