Anywhere in the EU is easy for you to work legally.
Canada, USA, Australia & New Zealand are harder but not impossible.
My year in New Zealand I just went on a 1 year working holiday visa.
Took me 6 months to get the visa though.
To Live permanenetly in Aus or NZ you need to set up a company and employ about 4 local people or have a company hire you for life.
Canada you need to meet specific criteria in order to qualify for residency.
I think I meet the requirements by about 1 point so its fairly stringent.
Or you could just marry a girl from there.
For a UK person the only places that speak fluent english are Gibraltar and Ireland, however a lot of places in europe will hire someone who is just speaking english.
Italy, France, Germany, and Spain have enough nationalistic pride to not want a foreign speaker but Austria, Belgium, Netherlands, Luxemberg, Sweden, Norway plus a lot of other countries all tend to learn it in school.
I have worked in Austria twice and I speak very poor german, however most austrians speak fairly good english.
I also worked on Sites in Rotterdam & the Netherlands with no problems.
Pick somewhere and then work out a way to make it happen.
I picked Gibraltar cause the weather is fantastic, you earn good and you can spend money in Spain, Portugal and Morocco fairly cheaply. plus its english speaking, you earn stirling, its VAT free, and getting a place across the border in spain to live would be very cheap.