I was wondering how long do fallout 1 and 2 usually take to complete? Will i have them done in 10 hours? Or will I be spending a bit of time playing them?

It all depends on how you approach the games. If you want to try a sneaky diplomat it might take a little bit longer because there might be some combat situations that you might have to reload a few times to get through them
When I played the Fallouts when they first came out, it took me about 1-2 weeks to beat each one and that was with just playing Fallout 1/2 and nothing else. School had a way of eating into my Fallout sessions XD.
Besides, there are tons of side quests to do in each game, more so in Fallout 2, and those should keep you occupied for a while.

it is possible to "complete" them in hour or so :)
but for me speedrun of F1 with most of quests (in that time i have known nearly all about this game, and i used lots of powergaming tactics) took me about 5 hours
playing thru F2 with all quests (and powergaming tactics) which i have known took me about 25 hours.
so it is somewhere between few minutes and few weeks