Can I use a LED TL in normal TL fixtures?

Yes you can. Both with LED starter and without.
If you have a fluorescent fixture with starter, you can still use the fixture without conversion.
You simply replace the old starter with one led starter and place the LED TL and voila ready.
Do you want to save even more on your consumption? Switch your ballast off by bridging. Then you do not need the LED starter and you quickly save 10w per ballast.
The LED TL must then be connected along 1. This is shown with scheme on the LED tl itself.