I have noticed that sailing to windward, I have a problem with the wind blowing the bow of the boat around, against the rudder. I have also noticed that if I release the jib sheet, the bow will respond better to the rudder into the wind. This has been a problem tacking while single handing, and while sailing with the "crewing challenged". I would think there are better cleats than the "belaying" type I use, and I wonder if the fairleads are either too far forward, or not far enough forward to tighten the jib sheets properly. Is there a proven way to lay out the fairleads and cleats?
Brit, it sounds like the jib is oversheeted. Do you have tell tales on the jib? Both windward and leeward should be blowing back at 90* when it is set properly. The fairleads need to be back near the shrouds (I actually use a block attached to the forward shroud for a jib fair lead) as a "permanent" position. The other thing would be to have the fair leads on tracks so you could slide it up or back depending on conditions.
It sounds as if Angie has diagnosed your problem. Over sheeting is a common problem, for novice sailors and those that are switching from Bermudian rigs to gaff. The headsail on these boats is too small and doesn't have a tall enough luff to be terribly effective to windward. This is typical of most gaffers, the mainsail is the real work horse and it's luff length and the yacht's appendages determine the boat's abilities close hauled. The headsail on a gaff, particularly one that is set well forward on a sprit, generates a lot of leverage over the "balance" of the boat. This isn't much of an issue with the wind approaching the beam or aft, but close into the wind she's a mule, pulling like crazy, yanking the bow up, which you have to counter with the progressively heavier helm.
Tell tails can position the fore and aft placement of the jib sheet leads reasonably accurately, as well as indicate proper sail set. To set the lead (fair leads, blocks, tracks, etc.) Bring her up to a close hauled course and look at all three sets of tails. With a good position the leeward tails will be streaming aft, and the windward tails will be also, but they could be just starting to lift a touch (just a bit). If the lead is too far aft, the highest windward and the lowest leeward tail will be dancing around. If the lead is to far forward ("powered up") the highest leeward and lowest windward will be fluttering.
To read them under way; if the windward tails start to lift, you're sailing to high and should adjust the boat direction by falling off a hair. If you're sailing too low or trimmed too tight, the leeward tails will flutter, so ease the sheet to correct.
Jib sheet tracks are a wonderful thing and I install them on everything, but they do look out of place on a gaffer. Many old gaffers had several pad eyes, mounted to the deck. They were positioned for different lead locations and wind strengths. A snatch block or single block with swivel was attached to the eye they wanted on the windward side, then the windward sheet was reeved through the new lead location. When the boat tacked, the new location was in place and the procedure was performed again on the new windward side which is now slack.
If you choose the pad eye method, use the flush mounted style (folding or recessed) so you don't trip over them as you move forward on the side decks. Their general location will be around the shrouds, but the exact spot needs to be fixed, underway. A yacht with external (outboard mount) chain plates, can't be sheeted in very hard. You could bring the sheet inside the shrouds, but you'll gain very little and likely just pinch the boat, loosing speed and making a heavy helm. Gaffers are much faster and easier to control if you don't try to sail too high. This just heels the boat over, shaves off lots of speed (which makes tacking more problematic) and makes the helm heavy. One or two extra tacks will get you there faster and more comfortably then trying to pinch her up tight and trying to sail closer to your destination.