Hello Millie,
Unfortunately, I doubt that you will ever find a record, i.e. passenger manifest, of the Isaacs family's arrival in the UK. I am fairly certain that the passenger lists for the short passage between continental Europe and the UK were not retained. The collection of passenger lists available on the well-known subscription sites are for sailings to the USA, Australia and South Africa.
Possible options for establishing the Polish home town of this family involve tracing Arthur's older brother, Solomon/Sidney. According to the 1891 census, he was born in Poland. According to the 1901 and 1911 censuses, he was born in East London. I can't find a matching birth registration, i.e. with MMN Beber, on the GRO site, so maybe the 1891 census was the correct record.
Have you looked for a naturalisation record for him?
Arthur's burial location is a bit of a mystery. It wouldn't have been unheard of for the remains of individuals to be transported back to London for burial. What is the date of death on the certificate. It would be really useful, if you could post his death certificate.
To do this, you first need to check that file is no larger than 500 MB. Click on the 'Attachments and other options' below the message box, and then 'Choose file'. Navigate to the file on your PC, laptop, etc. and click 'Open'. When you click on 'Post', the file will then be attached to the post.
The attached picture is of the gravestone of Arthur's father, Goodman. The inscription confirms that his Hebrew/Yiddish was Gutman ben (son of) Yitschak.
Do you know when his mother, Jane, died?
I'm also looking for occurrences of the surnames Merzinsky and Beber (and variants) in Polish records.
Justin