Lying on a CV is fraud
Get caught and you're in big trouble - fraud is a serious criminal offence (for which you would probably be jailed)
If you lie on your CV and are subsequently found out, you can be dismissed immediately. In theory the employer can sue you for all the wages they ever paid you. That doesn't tend to happen, but they do sometimes call the police (unlikely for a hairdressing/supermarket job). That dismissal can happen after any amount of service - so you can never feel secure in your job.
There is a big difference between lying - ie making up a fact which can easily be disproved, and exaggerating a little.
So, making up a job or qualification would be fraud
Saying you are 'fully conversant' with a software program when,in fact, you've used it a few times, you might get away with (as long as using that program wasn't a core part of your daily job or you could learn very quickly).
Three years isn't a very long time out of the jobs market, so I'm not sure why you're worried. Many people get jobs with 20+ years at home with the kids