I know this has been posted heaps already

here's my problem....

I want to check my fuel filler hose if theres crack or worn out and replace it.

but

the screws for the fuel tank cover in the boot are stuck tried all lubricants, tried tapping them as well but won't move at all

I saw in some post that you can heat the screws and that will make the screws break free from rusts but it might be the same as just burning my car cos the fume's very strong in the boot.
Please advise

thanks