These people are economic migrants and come to leech off benefits
Actually most Somalians in the UK came at the height of the Somali civil war well over twenty years ago. Hardly any have settled in the UK in the last ten years. Most non-white people claiming state support in Britain are not recent immigrants but part of long established communities. If you don't like the ethnic profile of British cities that's your pregorative but it's not true to say that the UK is full of economic migrants.
It is true to say however that the most overwhelming influx of economic migrants in recent years has come from Poland and that about a quarter of families from Poland receive some sort of state benefits. That's not to say they're unemployed. Their rate of unemployment is about equivalent to native Brits but as the UK has a much more comprehensive and generous welfare system than the USA you might be unaware of the plethora of income supports for lower earners or non-means tested benefits which are part of social policy. The Polish communiity has taken full advantage of that. No reason why they shouldn't.
tower hamlets
Tower Hamlets is a weird place. One of the poorest boroughs of London but also full of white collar 'city' guys and girls who live there for the convenience but it's always been a very 'ethnic' place, used to be a big Jewish community as well. London has always been very mixed socially, unlike American cities where you have good and bad neighbourhoods, black and white neighbourhoods. Even in very posh parts of London there is social housing and I don't mean tower blocks. Apart from a few areas and streets that are owned by the Crown or by the Duke of Westminster or the Tavistocks or whoever, there are many houses in those beautiful old Victorian houses that are owned by the Council or a housing association. You can pay a couple of million for a place and have a council tenant for your neighbour. Notting Hill Gate is a great example of a place where you'll find an old Etonian living next door to a plumber. Generally it works pretty well. It's part of the charm and uniqeuness of London. It's a wonderful city.
Tower Hamlets is ok. A few nutters of course but in general it's quite a safe place. I remember when I'd been living in Hampstead Village which was very white, upper middle class, herbal teas and yoga, you get the vibe. I moved across the Finchley Road to West Hampstead which is a bit more downmarket, went for a stroll up Kilburn High Road and it was like stepping into Calcutta :)) But it was a completely safe place and you soon get used to it. Never had a bit of bother there. London is ethnically and socially mixed and has been particularly so for a good fifty years. Parts of London like Tower Hamlets have been a melting pot for much longer than that.