Well I did the trip this weekend as intended.
The people at Mona could not have been more welcoming.
Spoke to Ldn Info most of the way - no need to contact Valley at the weekend. Mixed it with a couple of (Hunter?) jets in the circuit
Had a tube blockage on departing, so a hasty return with no A/S or altlimeter - a gentle suck on the static source (and spitting out a quantity of water!) by one of the FI's at the clwb, and merrily back to Stapleford.
Total cost of landing/parking @ Mona - £5
Had to pop in to Caernarfon on the way back for fuel - all very efficient and helpful there too.
Diolch yn fawr.