I have some doubts as to how realistic it is if we want to avoid the infrastructure collapse that is on its way due to private sector mismanagement of the utilities but I concur that we used to manage to run the country without spending more than we had ... so, in theory, it should be possible to do it again.
http://www.bbc.co.uk/news/uk-politics-24356569
http://www.bbc.co.uk/news/uk-politics-24356569