Disclaimer: I am the accommodation officer at Chester House, a halls of residence in Muswell Hill, north London.
I have found this forum to be useful in the past and I believe I have some useful information to contribute.
The closure of Barbican YMCA has thrown a spanner in the works with regards to the provision of reasonably priced accommodation in London for dancers especially those attending Italia Conti & Central School of Ballet
As a result we getting enquiries from both schools. Whilst we have had students in the past, our dance & musical theatre students tend to study at London Studio Centre (LSC), Urdang and Mountview.
You may wish to try the following alternatives, all have a shorter contract term than either Unite or Nido:
Hyelm: Old Street (better for groups)
Minimum Contract Term: Various
Cost From: 612.26 per month
Nearest Tube: Old Street
They also have accommodation in Hampsted
Sir John Cass Hall
Minimum Contract Term: 39 weeks
Cost From: 120.00
Nearest Tube: Bethnal Green (Central Line & Overground)
Claredale House
Minimum Contract Term: 39 weeks
Cost From: 126.00 - 138.00 per week
Nearest Tube: Bethnal Green (Central Line & Overground)
Ashwell House
NOTE: Female Only
Minimum Contract Term: 12 weeks
Cost From: 165.00 + VAT
Nearest Tube: Old Street
A useful link is:http://www.londonmet.ac.uk/accommodation/halls-of-residence/home.cfm
It's run by London Metropolitan University and has a long list of private halls of residence in London.
With regards to catered halls of residence there are two in London that I know of namely Ashwell House & ourselves.