HELP! he needs to know how i feel!

Okay so basically I work in a small shop, and have done for the past four years. Im nearly 20, so ive worked there since i was kinda young. Anyway, every so often this guy comes in, he's really lovely and always has a good conversation with me, but i get so tongue tied around him, i dont know what it is because normally around guys i like im pretty chatty. I think i might get like this because the guy is twice my age, he's probably old enough to be my dad, and i know people say age doesnt matter, but in this case, i really feel like he might just think of me as 'the nice girl from the shop' and may have never considered anything more. We have similar tastes in music and we both like a lot of the same thing, but i dont know how to find out if he could see me as anything else, or whether im just totally dreaming here. The worst thing is, i leave for uni in three weeks and i quit the shop in two so im worried that if i dont find out now ill never know. Please help!