Since you are speaking of "quid" instead of $$, I don't know what your local practice is. But in general, when you put in name, you are taking some responsibility (in case of future accident / suits)
But given you have NOT known him that long, I would NOT intertwine your fairs with his. It is much harder to have yourself remove once you decide to go your own way.
Just tell him you have a rule not to do this kind of stuff until you've know the person for few years.
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Of course if he makes a big deal of it, then maybe he is not kind of person you want to be your BF too long.
Good Luck.