Lack of undergraduate research experience and impact on PhD applications
Keep going at it!

If local colleagues only take students from 4th year onwards, there must be good reasons - like fairness, openness, transparency, risk assessment... Look forward to your 4th year and beyond :)

Also, how typical is your 'lack of experience'? If all students of your 'class' share this, you will not stand out negatively, and PhD recruiters will expect you by default to have limited experience. Then of course if you manage to acquire relevant experience, that will make you stand out from the crowd.

Your question 'what if not...?' seems to go far beyond your original point and your main ambition. 

Take it as a game and keep the flame alive. Keep looking for opportunities, and you are bound to find one that will fit your circumstances.

Another way to go at it could be to approach higher education institutions where you would be interested in applying, and ask them what their expectations are in terms of lab work experience.

This way you will have a clear vision of the standard you have to meet to have a good chance of being offered a place, and potentially a scholarship. 
You will not have to second-guess what they want any more, and you can focus on achieving what they look for, and more.