It should be fine if you look after it for the first month, by that i mean dont change the bar, clean it twice a day or whenever it feels uncomfortable and dont touch it with dirty hands! The chlorine in the swimming water should do it good as well as sea water because they both are pretty good disinfecters in their own right. just make sure u clean it asap when out of the water and if any irritation occurs just dont swim again!
If you get it done reasonably soon it shouldn't be too bad for your hoilday, only took mine about 4-5 months to be ok, maybe even less! Go get some advice from your local liscenced peircing studio! xx