I always get a bit panicky when a coin forks, worried i'll lose my stash...so what do i need to do, just click on the update (i have a normal computer windows wallet)
and it does it automatic?, will i need to change passwords, will it create new keys?..sorry if these are daft questions but i don't want to feck it all up on the last hurdle.

and a big thumbs up to the bitbay team

There is no risk of losing your stash, just make sure you are upgraded.
If it's the QT update here:
https://github.com/bitbaymarket/bitbay-core-peg/releases/tag/v3.0.0aThe QT just replace the previous QT with the file above and you are upgraded. That's all. Of course always make sure you have good backups.
IF it's the MARKETS/HALO client then download at the links formerly sent. Run the updater. Then rename wallet.dat to wallet-original.dat and then load then new Halo. Then load your two private keys from the file menu(file->open->normal account). Or if you have multiple accounts load each one in any order. Then once you finish loading them it should show a zero balance which is fine, just click the rescan button on the lower right corner. Rescan is different from resync as it just rebuilds wallet.dat. Once that's done you should be up to date. To be clear you don't need new keys. Your two private keys in Halo are your account (key1 and key.private). So just stay with that same account.