The UK couldn’t leave in October because Johnson’s opponents forced a delay via the Benn Act that they passed and he lacked the votes to get a Brexit deal through Parliament. His hands were effectively tied.
We had the election last week and the Tories won an 80 seat majority on a manifesto to get it done. It will now happen at the end of next month. There’s no longer any doubt the UK will be formally out of the EU on January 31 at 11:00 am.
Up in the air remains the nature of the post-Brexit relationship the UK will have with the EU and the heavy lifting part takes us to the end of next year:
Getting Brexit done is the easy part. The hard road still lies ahead in the future.
Johnson was clear at the time he would do no deal Brexit but then caved. Which was not the first time he caved. Boris actually voted for May’s deal. So I don’t know who he thinks he is fooling now.
13 September 2019 - Boris Johnson ‘won’t be deterred’ from Brexit on 31 October
... But despite the new law, Mr Johnson said he would rather be “dead in a ditch” than ask for an extension.
https://www.bbc.com/news/uk-politics-49690613
you are correct on all threes counts - the withdrawal deal is agreed and done
the uk will leave as a member on 31 january 2020
the new trade agreement will be hard - but not impossible.