Note, it can be difficult at times to tell the difference between a signature advertising spammer that posts HORRIBLE advice and an expert that is sincerely trying to provide you with GOOD advice.
Thanks for opening with that, and for telling me not to rush. That's pretty much what I wanted to hear. There wasn't a consensus of advice, and this doesn't fill me with confidence.
My worries were that I couldn't transfer/copy/move my wallet without knowing additional keys/passwords or having to do something clever, and/or that a software upgrade would loose my wallet or make it inaccessible. My experience so far has not been great - I lost 12.9 on an exchange that closed down and a few more coins in a mining group I can't access anymore and some from the Ubuntu machine I was mining from - loosing the rest of my wallet to a software update would suck.
I never really understood what I was doing, but had a wallet with some coins and figured I'd make the best of a bad situation when the machine started bluescreening - and then discovered I couldn't transfer them.
I've now got confidence that I can safely use that wallet on a different PC, and have located and taken a copy of the walllet.dat file.
I believe I can just download a new Bitcoin Core and use the same wallet.
So I've built a new PC, will get all the installs done, and hopefully its plain sailing after that.
Also somebody mentioned forks. Is this a thing that effects me?
There was mention of Electrum. And seems to be a lot of different wallets out there. I'm assuming I can ignore this as noise?