As in the title if you buy a tube amp do you need and effects loop for pedals. As it stands now the only pedal I know I want is a gain pedal but I might want an EQ or other pedals. Would it be a big deal if you didn't have the loop?
You don't need one per say, though if you are using distortion from your amp then certain effects may sound better in the loop rather than before the amp.
"gain" pedals don't go in the loop, so no. The loop is useful if you want to get distortion from the amp's preamp and put things like delay/reverb/mod in the loop. Also good if you use a multifx and run the output stright into the power amp.
you don't need it its all about taste and what kind of sound you like