My subscription last until 4/20, if I cancel it now will I still be able to get any UE4 update and have access to the market place within that time?
Yes, you will.
As Artless said, yep! Canceling only changes whether your subscription will auto-renew on 4/20, it won’t change the fact that your subscription will stay active until 4/20.
You’ll also continue to receive any hotfixes to the 4.0.* version of the editor, even after your subscription expires.
and we can pick it right back up when we like as well, correct?
That’s right, you could wait a month before re-subscribing, for example, and you would then get the latest version and access to previous versions as well. You’re just missing out on those new versions and content releases until then. 
Thank you everyone! $20/month isn’t too expensive for me, but I’m a bit tight on money right now(I need to upgrade and buy other software). I’ll re-sub later in the year.
@Epic, thank you for having such a flexible subscription model, you guys rock!
What is the planned update schedule? Is it going to be at a fixed time each month or just as they are ready to go?
Also if we unsubscribe are we still able to download the versions of the engine that we used during our subscription or do we need to make sure to keep copies offline?