Buying a property and breaking renewed rental lease before commencememt

Hi peeps,

I am in a unique situation, just wondering what are my legal rights please.

I am currently renting an appartment in Melbourne and had been actively looking property for purchase. Also, initially made few offers , but it didn't go through successfully.

Earlier, my rental contract was about to finish by end of September 2020. My real estate agent started chasing up for renewal of lease by mid of July. During the renewal discussion, I requested the possibility of signing month on month or three months contract , but agent mentioned that they can do only 6 or 12 months. Since, I was not confident of buying property in next few months, ended up renewing my contract for another 6 months, even though my preference was three months.So, summary is :

a) Current or Old lease ends only end of September 2020
b) Renewed commences early October 2020 and ends on March 2021

Whilst, I continued property search and now managed to successfully sign an offer for the property. I can negotiate with Vendor to perform settlement by end of September 2020.

My query is :
a)As renewed or new lease come into effective only from start of October 2020 and my existing lease has not ended yet (valid until end of September 2020), can I break the renewed/new license without having to pay huge money for rest of my 6 months lease period please (if I don't find anyone for lease transfer in next few days) ?

b) Also, I am a first home buyer and planning to claim first home buyer stamp duty discount. If I can't come out of the lease, just wondering whether it will have any issues for me to claim the discount please ?

PS : I understand the owner situation as well, but I just want a fair deal for both of us. I understand that I can negotiate with owner as well, but just wanted to understand my legal rights please

Thanks,
Melbie