I do an occasional internet order. I've usually used Beermerchants.com for my annual Christmas selection, but this time used beerofbelgium.com. The former is good for a wide international selection but more expensive as it's all UK imported, the latter great if you like your Belgians.
As it's a warehouse in Flanders it's very cheap for the beer, but the postage is by weight - a mate and I paid €20 for our joint 50 bottle shipment.
Or if you're local to Brum (I'm not anymore), I've been led to believe that Stirchley Wines have it. Where it probably costs £5 for 33cl rather than €3.60.
Worth every penny, either way.
Edit - I've just remembered, The Wellington and Post Office Vaults both have it. Although the last time I was in the latter was that horrendous friendly against Parma in 2014. So I assume they still do.