I don't know about the UK but liquid Albenza can be purchased at feed stores.
You may want to let us know why you would want it, seems to me that because Albenza starves worms to death, there may be a better option.
I use Ivermectin cream topically. It's a horse wormer that comes in a plunger with notches so you can measure the dose. I mix it half and half with anti-itch cream and it's working for me.