I can't see there being any issues whatsoever doing so. Just enter your account details in for PPPoE and should be good to go.
Only issue is BT won't give you support without the HH3 in place so keep it handy so you can plug it in if you ever have any problems with your line.
I've used 3rd party routers on many of my friends connections successfully, I see no reason Almond+ will be any different!
