Some facts to take into account:
Net immigration into the UK in the year before last was around 750 000. Boat crossings came to only around 41 000 (It's a while since I looked at the figures so I may be a bit out). The net migration figures coming out in a couple of weeks are going to show that net migration fell by a significant amount last year.
There has always been illegal migration into the UK (and there probably always will be). The growth in boat crossings simply reflects that the back of the lorry route was made much more difficult by millions being spent to deter it.
A person arriving in the UK will struggle to get a visa if they can't provide evidence to show that they can fund their stay. In addition - most visas are marked 'NRPF', which means ?no resort to public funds?. In other words, the holder isn't eligible for benefits.
A person applying for asylum in the UK receives 'benefits' in the form of basic accommodation, basic meals and ?8.66 per week for their outgoings. They aren?t permitted to work - the theory (unsupported by any evidence of which I am aware) being that allowing them to do so would encourage others.
It seems slightly daft to me to suggest that immigrants are coming here for the benefits. Are we to believe that people will pay ?thousands to people smugglers and risk their lives in the channel for ?8.66 per week and the right to share a room in former hotel and eat crap food?