Minfigures Series 2 is now available at WH Smiths stores, nationwide, subject to stock.  They’re priced at £1.99 each and are usually on display at the payment counter.  Ask nicely and they should allow you to search through the box using your chosen identification method (barcodes printout, iphone/android phone application, feeling the pack, using the force or just plain pot luck).

On the subject of the Series 1 sets, it appears that Asda stores are still getting stock of these or at least my local large store is.  Might be worth checking out the toy aisle if you’re in one.