If you're just down the road from a high-powered Freeview transmitter you could probably stick a wire coat hanger in yout loft and connect it to a TV set with any old flex and get a good picture. (OK, that might be a bit of an exaggeration but I'm sure that you'll take my point). However if you're a long way from high-powered transmitter (or the only signal you can get is from a low-powered local booster transmitter) then getting any picture at all from most types of loft aerial can be nearly impossible. So it's hard to provide a 'one size fits all' answer to your question.
TV reception where I live is very difficult. Half of the houses around here have aerials pointing at one transmitter, with the other half having aerial pointing at another. They're nearly all elevated by being on top of long poles and invariably 'multi-element' types. That's despite the fact that there's a covenanant on all houses on this estate, prohibiting external TV aerials; everyone here simply knows that it's impossible to use a loft aerial!
However when my TV aerial fell down a while ago, I realised that I couldn't afford to pay to have a new one fitted (or for the hire and transport of a ladder to do it myself), so I decided to attempt the impossible and see if I could get a loft aerial to work for me. Fortunately I know quite a bit about aerial design (I've written magazine articles on the subject), so I was able to carefully research the most likely aerial for my needs. This is what I chose (and what I'm most definitely recommending to you):
http://www.maplin.co.uk/p/nikkai-tri-fold-outdoor-tv-aerial-a22hg
I still needed to put a couple of signal boosters in the line to get it to work properly but my TV now reports 'Signal strength: 100%. Signal quality: 100%'.
I actually just used the cable I happened to have lying around. Unlike satellite cable (where there can be big differences in quality), the stuff you can buy in 'discount' shops is probably just as good as anything which is claimed to be of exceptionalquality elsewhere. Any 'low loss' 75 ohm co-ax should be good enough for your needs. Maplin sell a suitable product at just 59p per metre:
http://www.maplin.co.uk/p/low-loss-tv-coax-cable-brown-priced-per-metre-xr29g
So I've given you my suggestions for an aerial and cabling. Whether you'll also need a signal booster depends upon the signal strength at your location. However I'd probably use one of these in your situation:
http://www.maplin.co.uk/p/nikkai-aerial-amplifier-with-digital-bypass-4-way-l23ag