I know it's hard to get Mexcian foods in the U.K., but if you can switch over from the Italian foods to Mexican foods, you can still get the carbs without the wheat. Tortilla chips are made from corn (still check the label to make sure they haven't slipped any gluten in) and traditional tortillas are made from corn too, although most are made from white flour. The corn ones aren't as good as the flour ones (in my opinion)--namely because you have to heat them up in order to make them soft--but you can still use them for your faijitas and enchiladas and the like. I've heard of potato bread, but I don't know if that involves any wheat or not. American-style corn bread (made with corn meal) does not contain wheat. And bannocks are good; I can't remember if they call for flour, but I know they're predominately oatmeal. If you didn't sweeten them, they should do for a bread substitute.
If you are intolerant but not allergic, I would think that would still entitle you to some wheat daily, but just not as much as the average person can consume. I think rather than going cold turkey you should ease yourself down. Trade the pasta in on Mexican or Chinese foods and replace your carbs with rice and corn. I do know the U.K. has a much better selection than most U.S. cities of Indian and Asian restaurants--both of which should be rice-based and mostly, if not totally, wheat-free (except for the noodles). I wouldn't sweat the gluten that's added into every little thing, but I would try and cut back the large quantities of it that you consume, namely in pasta. If you find yourself about to die for some pasta, at least try and get some spinach or vegeatble pasta. Yes, there's still wheat in it, but there should be a slightly smaller amount, since some of it has been replaced by the spinach, etc.
If you get better after giving up bread and pasta, then you probably are gluten intolerant. Probably want to see an allergist to see if you are really allergic, or just have an intolerence (and thus know whether you can tolerate small doses or need to stay away completely). If you give up the majority of your wheat products but see no difference, I would think you're not wheat intolerant.
Walking is good to combat gas (or period) cramps, so you may want to try taking a walk every day. You're lucky in that the U.K. is walking friendly (what with all the sidewalks and the people who actually DO walk to get where they're going). If you're nervous about getting sick and walking too far, then try walking around the block or to the end of the lane and back. You'll figure out pretty quickly whether or not you're too sick to go far, or if you stand to walk into town. That should help combat your cabin fever and may even help your depression. Sometimes it's good to just walk and think and look at the grass and the sheep and the historic buildings. Helps the sress, which can make IBS worse.
I found the countryside in Wales and Ireland beautiful even when it was raining (but of course it was all new and wonderous to me; if you live there, you take it for granted, same as I take mountains for granted here in Tennessee). When I was in Ireland, I walked to the grocery store and back every day (probably between a mile and a half to two miles round trip), even on the days I wasn't working. It just felt good to be out of the house and to be moving and to enjoy the countryside. That and I only bought enough food for the one day, so it kept me from overeating. When I lived in town, I spent my Sunday afternoons climbing the 100' round tower at the high end of town. I was so in shape then!
Oh, if nothing else, cut out all alcohol, carbonated drinks, coffee (which even decaffeinated can be overly acidic) and caffeineated products (except tea, which has little caffeine and good benefits). Caffiene does a number on me and some other people, carbonation can make your gas worse and beer and wine tear a lot of people on this board up (although a lot say they can tolerate hard liquors).