It'll sound crap. It is do-able, but, it'd sound crap
Its a tube amp anyways, you want to mic it. You can get dynamic mics pretty cheap. A while back me and the guys in my band wanted our own mics, so we pitched together and got a pack of three behringer dynamics for ~£20. Ok, so, they arent amazing. But there isnt a huge deal of difference between them and say an SM-58.
Also, while not too good, you can get condensor mics for under £20 if you look in the right places.