If Goo Gone and Goof Off are not available in the UK, Acetone (aka Nail Polish Remover) is a good alternative and is widely available anywhere at low cost. (our local "Dollar Store" sells it.) Acetone is one of the ingredients in the original Goo Gone and Goof Off.
Recently, I came across two ancient bottles of cigarette lighter fluid in the back of a storage closet. I have no use for the stuff and wondered how best to dispose of them. Then I remembered that lighter fluid is made from naptha which is an excellent solvent and is often also used as an ingredient in various Goo Gone and Goof Off type products. I just used some of the lighter fluid the other day to get the sticky label residue off of a glass jar I want to repurpose. Worked great!