Isopropyl alcohol will work every time and do no damage to any paint or plastic - the difficulty is getting hold of a small quantity in the UK (easy in lots of other places). You could try your local chemist who may be able to advise you, alternatively check at paint stores, auto parts suppliers, etc. next time you are abroad. Buy the smallest size you can get (sometimes as much as a litre) because there are lots of uses apart from dissolving sticky glue, such as spot remover (felt/fibre/ball point pen ink, etc., etc.).