You can't afford £10 or so for an iron supplement? Have you tried the tablets? They might not cause any problems for you.
Seems a bit silly to get yourself so worked up over low iron levels. Try and relax.
http://www.tesco.com/groceries/produ.../?id=285353353
Check these out. One serving (which isn't a lot) gives you 90% RDA of Iron. You could eat two servings if you need to put weight on. Eat beans, lots of green veg and try and get a supplement you can handle.
Your levels will shoot up in no time.