Hi i really need advice on home hair relaxing. I have curly caucasian hair and need a reccomended preduct?

my hair is quite long, caucasian and in fairly good condtion, iv heard its good 2 do some conditioning before relaxing 2 prepare hair, im also having a cut 2morro 2 get rid of split ends prior to relaxing. i need advice on the product to use as i dont have a clue! people hav reccomended uring a product available in boots but its designed for african/asian hair so i am sceptical about its safety as im sure caucasian hair will react differently 2 it. i hav also heard that using a product for children is better 4 hair. also what is lye and no-lye? i dont want 2 do any damage to my hair, well i know that relaxing alters the hairs structure but i cant go on having curly hair, it really gets me down and i no longer feel comfortable going out as its so unruly. i long for straight hair and if anyone can help me, with advice and reccomending what i can use. i must stress that i cant afford a salon treatment!!! iv read of people sucsessfully using home kits. any help would be great. thanx!!! x