Well, basically he’s a stranger but he’s English. An English in Belgium. That’s going to help my project. It’s about English culture anyway could I use intrude or impose in that case or would it be better to say I don’t want to bother you...?
In broad terms:
You impose (on someone) if you are going to ask them to do something that will be time-consuming and that might be inconvenient for them.
You intrude (on someone) if you interrupt what they are doing (usually, but not always when, they are clearly concentrating on something.)
Both of them are probably far too formal and too strong unless the person in question is very important/of high status and is not well know to you personally.