Hi @rodney67,
Welcome to the Bunnings Workshop community, it is wonderful to have you with us.
To give you the best advice specific to your issues, could I trouble you to upload some photos? Let me know if you need a hand with this. I am happy to help if required.
Things like silicone, foam infills, aluminium angle, aluminium sheet and aluminium flat bar are commonly used to seal gaps in sheds and might be useful in your situation.
You might also benefit from having a look at these discussions from the community -
Once we have a better idea of the specific issues you are dealing with, I will assist further.
Jacob
