if you have good coverage than a decent aerial in the loft should be fine... however nobody is going to be able to give a definitive answer. the only way to know for sure is to try and see.
I'd put the aerial in the loft, don't worry about putting the cable in neatly to start, just hang it out the loft hatch and try it. then if it works all well and good and you can run the cable neatly, if it doesn't work at least you've not wasted too much time and effort finding out.