If your boyfriend is quite clingy he will probably get even more so at university as he will think that you have lots of opportunities to meet new guys, which may threaten him a bit. I reckon if you want to stay with him though you can get through this without cutting yourself off from everyone else.
I think the best thing to do in this situation is to be honest. Just tell him that you really want to do all the freshers events at the beginning of term with your new flatmates, and to get to know them well. If he questions this, just say that you really don't want to be seen in your flat as the girl that never socialises with her flat and sticks to her boyfriend. Just keep assuring him that whenever you go out clubbing you're just doing so to have fun with your new friends and although some of your new friends may be guys, they will only be friends and nothing more. I'm sure you won't break up whilst you are at uni, and I'm just saying this because it could happen, but the worse thing would be to spend 100% of your time with your bf and neglect all other potential friends, and then find you break up and have no friends to turn to.
Relationships are all about comprimise, so just like you will have to make sure you don't cross any boundaries and make sure that you don't do anything that could constitute as flirting with your new male friends you have got to let him know that you want to have a balanced uni life and at least for the first few weeks, make an effort to make friends at uni.