BRP card to travel

Hi! Applying for my provisional license, and need to send in my brp card. I'm traveling to the states in 3 weeks - do I need my brp original card to enter the country again when I return from holiday? Or could I provide my passport and a photocopy of front and back of BRP? Thinking I need to extend the deadline of my license application

You must have your actual BRP card with you when you re-enter the UK... it is your visa and your only proof of right to live in the UK.

Your passport and BRP card go hand-in-hand, you cannot re-enter the UK with only one of them. You wouldn't try to enter with a photocopy of your passport instead of your actual passport... same goes with the BRP.

I would wait to apply for your provisional licence until after you have returned home from the US.

Definitely wait!  Apply when you get back.   

You will get an automatic refund of the fee you paid if you do not send in the completed form by the due date so definitely wait to re-apply when you get back.  I think you may also be able to request an extension if you call them number on the form.