They can be used in virtually any bookshop in the UK like Waterstons, Borders etc. (see http://www.booktokens.co.uk/
for a list).
As i have quite a few of these book tokens you can choose in which denominations (£10.-, £ 25.- of a mixture) you want them.
I would also consider splitting in 2 lots of £50.- tokens (or if interested can provide more than £100.-).
No fb here, but can provide ebay seller id with fb of 2500+.
Price: £ 85.- including recorded delivery.
Payment by BT, PO, cheque or BALANCE FUNDED paypal (can also accept other paypal but you'd need to pay the fees).