Brit dopers: where to buy a travel pack

I’m looking to buy a travel backpack at least 70 litres plus quite a large attachable daypack. Can anyone suggest any online stores similar to Millets and Blacks (I’ve checked both of those and they dont have anything that fits the bill)

Try Snow and Rock. They’re very good, and the assistants in their shops are extremely knowledgeable and helpful.

Also try Cotswold Outdoor

thanks all!!