Hodges Figgis voucher

Hey all - Got a lovely voucher for HF from my wife. I know they're owned by Waterstones now, so I was accidentally browsing the Waterstones website to see what I'd like to pick up. Realized and swapped to the HF website, but most of the stuff I'd taken note of from the Waterstones store aren't listed on the HF website.

Does anyone know if HF can order whatever if I pop in, even if it's not on their website? These would all be books that've been published in the UK, so not super rare things.