@Karina In the UK a clause like that which would effectively stop you from earning a living is 100% not enforceable, it's a joke. I know how that works having moved around between NetSuite partners over the past 13 years.
The only real slight possible exception is if you were something like CEO and privy to highly sensitive commercial information that would give a competitor an edge and be damaging to the business you left.
Dev's that worked on my team left and were threatened with legal action if they moved to another partner. The new employer basically said "bring it on, it'll go to court, it'll get thrown out, good luck" and said they'd cover any legal fees the devs might incur.
It never went to court, they just thrashed about making threatening noises and tried to frighten the devs.
Which actually was true to form and one of the reasons the devs left, nobody likes a bully.