Suitable Attire

I help out at our local Church with the children's services. I have no formal role or title, and haven't done any training for a long while (which I probably should, note to self and to PCC and/or anyone who offers such things) so, unlike the clergy who have a uniform and only have to decide how many holy layers to add, I have to decide on something suitable to wear.

It's a formal Church, but this is a "family" service (for which read we are attempting to attract school age children even if what we usually get is toddlers and older members of the congregation who come along to support). It's the weekend so I don't want to have to dress in work clothes but as I got my jeans filthy in the garden yesterday I will be wearing a smarter pair of trousers so it's only the top half I've got to worry about. What I'd like to wear is this T-Shirt

but I think it might not go down well - and anyway it's not mine. I'll probably even chicken out of the Martyn Joseph "You can only trample people down for so long" one, if only because it's obviously meant for a flat male chest rather than a bumpy female one and rather difficult to read on me. Decisions....