I have found this one for £700. It's a 2015 model NON-RETINA. Is it best to buy one with or without retina? I've heard you can't upgrade the retina model.
And is the Nvidia GPU good on this model ?
Specification
-- 15 inch LED screen
-- 3.3GHz Quad Core i7 Boost from 2.3GHz
-- 16GB Memory
-- 1000GB / 1TB Solid State Hybrid ( SSHD )
-- 2 x Graphics Card
Intel HD 4000 ( 1.5GB Memory )
Dedicated Nvidia GeForce GT 650M
-- Thunderbolt and 802.11ac Wireless
-- 2 x USB 3.0 ( speed 5000mb per second )
-- Battery is NEW only 35 cycle (max 1000)
I do owe the same 2012 quad-i7 model. Got it 2nd hand for far more money than your occasion is, but I'm really happy with it.
Fast, silent. Great performance. Doesn't get to it's limits doing the stuff I need it to do.
I use it mainly for paperless-office with DEVONthink /batch-scanning/batch-OCR and for light-weight video/photo-editing. Don't know, if it/the GPU will meet your needs and the needs of AutoCAD.
I preferred that 2012 non-retina book over an rMBP cause I can swap my 1TB SSD to a bigger one, whenever I need more space and SSD's get cheaper.
My main driver for on the go is an early 2008 MBP 2,4GHz Core2Duo (silver keyboard, non-glossy display) with a 500GB SSD, 6GB and ElCapitan. It came at 100$. Plus additional cost for the SSD. Great device. Has got an ExpressCard for USB3.0. Get's most of my jobs done and the bright non-glossy display is great for watching videos.
Don't ever go for those 2010/2011 i7 DualCore. Lot of them have a faulty graphic-chip and there's no more Apple-support due to lack of spare parts. I do also have such a 2010 15" MBP. My so called "StrokeUnit". Got the faulty GPU mended, but it's a red-hot and without additional software to power down CPU-boost and 2nd-GPU it's fans are always at max.
As others said: a real quad-core runs much smoother than a dual-core and a 15" display is more convenient than 13" one. I have "old"-eyes and do not benefit from retina and a 13"rMBP having a better screen-resolution than my 15"-rMBP. But if you need to travel a lot, the 13" might come in more handy...