Short term extension options upon spouse visa expiration

Hello everyone,
Wondering if I could get some advise for my situation.

I have a UK settled husband (with UK ancestry ILR) and I'm holding a 2 years spouse visa which expires in this end of July. Originally we were supposed to leave the UK this July before my spouse visa expires.

However, our circumstance has changed and we now have to stay here until the end of October, and this fact turned out just recently. Therefore, I have not prepared any visa extensions as we were supposed to leave, now I have to make an action avoiding expiration of my visa.

What are the options available just to stay another 3months until October?

Do we have to apply FLR (another 2 year spouse extension) just for this 3 months stay ?

If so, premium visa application service now has no slots for availability before expire, we have to do only with post application, though while the process of extension visa by post is being processed, our leaving date is coming.... (I heard post application takes at least around 12 weeks or more)

This means, we pay over 400 GBP and might not get extension visa on time, as well as having the anxiousness I might not get my passport back by our departure of UK in October. For this option, we will pay 400 GBP just for nothing.

Is it possible for me to go to Paris or somewhere just before expire and come back here afterward to get stamped on passport? (I'm a Japanese within exception countries for short stay visitor visa) Or is this option too risky? (might be refused?)

Only we need is wanting to stay until this October. I called immigration bureau though they just indicate about FLR. (and they were so unfriendly manner too so were not supportive)

Thanks for reading and your time, I appreciate it if you could give me some clues.

Kind regards
Jun