Advice on Travelling between London & Birmingham for 4 days

Hey all! From Singapore here :) I'm planning to attend the Crufts dog show in March at Birmingham NEC for about 4 days, am staying at the London Euston area.

What would be the easiest / most economic way to travel to and from the show? Would that be taking Avanti West Coast from Euston? I also noticed that there's a weekly season pass - is that something worth considering or too expensive?

And if you guys have any advice on attending Crufts or any cool astuff to check out in London, let me know too! Thank you in advance!