TKR99 said:
I might have little choice but to revert given the laptops pretty unusable without wifi access as I can't download anything directly to it & it equally can't connect easily to my network etc. But will do so much happier if I know I can easily repeat the upgrade for free later on.

Since you have no internet after upgraded to Win 10 so there is a very high chance that you have not yet activated your Win 10. If you want to upgrade to Win 10 again, you probably can do so in the same way as you did before just make sure you don't do a clean install of Win 10 unless you are pretty sure that your previously upgraded Win 10 had been activated successfully, e.g. you have successfully connected your laptop to the internet using wired means. If you are not sure then it is better to assume that it has not been activated.