Encoders for diy custom farmbot

So my custom bot is coming along nicely. X and y frame and carriages done, rPi and Arduino programmed, plastic parts being printed. I’m stuck on the encoders. The ones I bought are absolute magnetic angular position sensors and I don’t think they will work. Farmbot are out of stock of their motors with encoders built in. So I am looking at separate quadrature encoders from Farnell of RS but I don’t want to make another erroneous purchase and so far I can only find ones with an A and B output but the RAMPS shield on a farmbot seems to need 4 outputs from the encoder ; A B Aq and Bq.

Can anyone give me any information on the encoder aspect of the farmbot and what the software expects and if using separate encoders which ones will work and where can I get them from (preferably in the UK)

Cheers peeps