I'm not a lawyer, but first clause and it's variations are common in contracts and it's ment to protect the rights of company for IP developed at work.

It definitely is not ment to apply to things u do in your free time. As long as you do your stuff on your own hardware, it does not relate to IP or source code your employer owns, or does not provide competing services to your employer's customers, I don't see how your boss interprets that clause in such a way.

In addition I would check how 'work' is defined in your contract, since you are in EU as I am, I believe it usually mentions place where work is performed and work time from - to, work load (how many hours) and description of work. If the contract defines 'work' as any activity you do in your life that would be pretty jaw dropping.