OP do you really think that many of these immigrants who come for whatever reason to this country get employment on the day of arrival?
It can take some time for them to adjust to UK way of life plus I am sure many of them wouldn't be much conversant in english.
Ofcourse this puts strain on country resources but from human rights perspective some help has to be given to them initially.
The other option is to let them starve to death on UK soil, if that's what you want?
Ofcourse I never agree to anyone being on benefits for a long time.
OP if you simply state that doors to immigration in this country should be closed then you should take this issue with relevant authorities
Besides more nationals in this country are seeking benefits than recent arrivals.