Sarah,
You need to send off the photos and the form to the Club HQ in Lubenham - address at the top of the page - Don't forget to either include a cheque for
the valuation fee, or fill in the credit card bit on the back. If the valuation is for more than about £4K, you might need to take the car
to the HQ for a direct valuation, or they might ask you to take it to be seen by your local area organizer to confirm its condition.
Read more about it here
http://www.tssc.org.uk/insurance.asp
Incidentally, agreed value valuation certificates issued by the Club are NOT transferable to a new owner - a new owner has to get their own new one.
They are also only valid for 2 years at a time.