Another Ziner recommended the Columbus Hotel near Paddington - http://www.delmerehotels.com/columbus.html

It is a two star hotel and appears to be a bit nicer than some other hotels along Sussex Gardens.

The Delmere is a sister hotel to the Columbus also in that area - http://www.delmerehotels.com/delmere.html

It is a bit pricier than the Columbus (but the weekend internet rate is still within your 60-70 pound budget).

A third alternative is the Vicarage Hotel in Kensington - http://www.londonvicaragehotel.com

Cheers, Mark Los Angeles