hello. there are 35 symptoms of menopause/perimenopause, the most well known are hot flashes, and periods which come and go, heavier or lighter, and then stop. but for a lot of women they are the easiest to deal with, it's all the others which cause such problems. there's anxiety, sleep disturbance, dreadful pms (which for many is the first sign of peri), stomach issues, loss of confidence, loss of libido, worry about you health, thoughts of doom and gloom, etc., etc. if you do a little research you will find them all.
you can have them from any age really, as some ladies have an early menopause, but i would guess that it's mainly from 40-45 onwards. if you've any specific questions about something you're suffering from, ask away, someone here will have an answer for you. good luck.