General rule of thumb for financial related stuff is six years from the end of the financial year they relate to.
Pension agreements / shares / mortgage / rental / loan documentation / life insurance / car finance agreements would be six years from the end of the financial year in which they ended or were sold.
Utilities (energy, phone, council tax, tv licence) I used to keep for three years when I had paper copies.
Bank / credit card / utilities / council tax/ tv licence / insurance / pension statements should all be available online (inlcuidng the history).
Check all the online accounts to see what history they hold and download it to file electronically (hard drive with cloud backup)
Get into the habit of doing it regularly - either every couple of months or when you get an email saying the new statement or bill is available.
Sign up for paperless billing so they stop sending stuff through the post.
You then only need to keep anything paperwise that you haven't been able to download electronically for the relevant timescales as above. Shred everything else
I tend to keep the original paper copies of things like life insurance/ mortgage / car finance agreements etc even if they are available online / electronically.