Im ready to resign from my current role, Ive not resigned from a job in over 20 years and back then i told them to fuck off and didnt go back.
Im assuming thats not acceptable these days.
Whats the correct way to resign, by email (my manager is in a different location), by phone, carrier pigeon?
If heās in a different location, email.
Actually, if thereās some sort of HR handbook iād Double check that first
Email to your line manager and a copy to HR is all you need to do. I would confirm the date you intend to leave in the email.
Full breakdown and flounce in front of as many staff as possible.
Prepare a long rambling and very personal leaving speech and cry your way through most of it. Make it as awkward as possible for anyone that has to witness it.
(Maybe back this up with a formal letter of resignation to your line manager).
Many moons ago I phoned HR and asked how I should resign. I was asked why I wanted to quit and when the HR person realised that it was partly related to stress, he suggested that I might be better advised to go off sick. It turned out to be very good advice. I was very lucky that a good person rather than a company man answered the phone.
Thatās extremely rare indeed! The actual job of HR is mostly about minimising corporate liability, not actually doing anything for the rank and file.
Handbook just says 1 months notice, its pretty vague.
I had to request a reference last week as part of the SC for new job, HR seemed really surprised i wanted a reference and unsure how to deal with it.
Iād prepare a short factual letter, save as a pdf and email it to your boss and HR.
A former colleague of mine resigned by email entitled āSo long and thanks for all the fishā. 
ā¦ and it was completely justified in that case.
Should reasons be given or is it ok just to say pastures new?
Depends on you relationship with your manager. These concerns could be raised at your Exit Interview, if they do one.
The biggest thing is to make sure you donāt burn any bridges, and the easiest way to do that is to say as little as possible.
You can say what you like 
However if you want a reference etc then its best to be cordial, thank them for the opportunities or development etc that they have given you etc. A brief idea of why youāre leaving, which can be as vague or specific as you like.
Or you could just say youāre leaving because of Brexit and keep them guessing!
Depending how long you have been in your current role you might find it is longer than 1 month. Check with your HR dept.
Been here 6 months, a month is all thats required.
Already had reference from HR, all that is done and dusted its just the formality of resigning now.
Then you can be as brief as so long and goodbye motherfuckers.
The Joyful prospect of āLe Power Flounceā is often hampered by reference requirements - One of the many things I dislike about reality.
Also the need to work out my redundancy period dues to money reasons.