I am looking for a shoot myself, and like you I would be happy to take a "second place" holding the lamp or just carrying stuff for the experience of learning rather than anything else. It is very hard to get "in" on somebody else's shoot. But your attitude in the way you ask the question speaks volumes about you (in a very positive way). Do not give up asking and good luck in your quest.

Another point is that if you join a club then you get to know the members on a personal basis, and when people know you they are more likely to invite you on a shoot with them. Join (or at least visit) every club in your area and get to know the members, You never know what may result.

For example, Tawd Vale is not that far from you (my club), come and visit us, you may find somebody who would be willing to take you along. (I offer no guarantee, but it is worth a try)