Report to work before signing offer letter

I had succeeded in an interview on 29 April 2016. I'm asked to report to work on 2nd May 2017 which I agreed. The offer letter I'm told will be ready in between 2 May 2017 to 5 May 2017. However after reaching home and think through again, there are certain terms and conditions which I haven't go through yet and regret the decision.

If I report to work on 2 May 2017 without signing the offer letter yet, am I bound to the rules and regulations of the company (i.e considered accept the offer via conduct)? Can leave unconditionally after received and reviewed the offer letter and found I can't accept the terms and conditions in the offer letter, despite reporting for work?

Can leave unconditionally after received and reviewed the offer letter and found I can't accept the terms and conditions in the offer letter, despite reporting for work?
Normally un-confirmed staff can resign in 24 hrs notice, so no problem.